WEBVTT
00:00:02.040 --> 00:00:04.840
I have a number, 𝑥.
00:00:04.840 --> 00:00:06.200
I add three to my number.
00:00:07.240 --> 00:00:09.200
Then, I divide the answer by five.
00:00:10.520 --> 00:00:13.680
My final answer is 2.78.
00:00:15.160 --> 00:00:22.440
Calculate my final answer if, instead, I add five to my number, 𝑥, and then divide by three.
00:00:24.440 --> 00:00:25.960
This is a two-step problem.
00:00:26.640 --> 00:00:29.760
Firstly, we need to work out the number 𝑥.
00:00:30.360 --> 00:00:35.160
Then, we need to calculate the final answer using the new operations.
00:00:37.280 --> 00:00:40.800
We were told in the first line that the number is 𝑥.
00:00:42.320 --> 00:00:45.120
The second line told us that we add three to the number.
00:00:45.880 --> 00:00:48.320
This is written as 𝑥 plus three.
00:00:50.040 --> 00:00:53.160
The third line tells us that we divide the answer by five.
00:00:53.920 --> 00:00:58.640
This can be written as 𝑥 plus three over or divided by five.
00:01:00.120 --> 00:01:04.640
The fourth line tells us that the final answer is 2.78.
00:01:05.120 --> 00:01:11.560
Therefore, 𝑥 plus three divided by five must be equal to 2.78.
00:01:12.960 --> 00:01:18.120
Our first step is to rearrange this equation to calculate the value of 𝑥.
00:01:18.640 --> 00:01:21.120
We will do this using the balancing method.
00:01:23.160 --> 00:01:26.880
The opposite of dividing by five is multiplying by five.
00:01:27.480 --> 00:01:31.800
Therefore, our first step is to multiply both sides of the equation by five.
00:01:33.640 --> 00:01:37.760
Multiplying the left-hand side by five means that the fives cancel.
00:01:38.480 --> 00:01:40.800
This leaves us with 𝑥 plus three.
00:01:42.520 --> 00:01:47.000
On the right-hand side, we need to multiply 2.78 by five.
00:01:48.160 --> 00:01:52.760
Typing this into the calculator gives us an answer of 13.9.
00:01:55.040 --> 00:02:04.080
Our next step is to subtract three from both sides of this equation as subtracting three is the opposite or inverse of adding three.
00:02:05.760 --> 00:02:08.800
Once again, on the left-hand side, the threes cancel.
00:02:09.400 --> 00:02:11.080
This leaves us with 𝑥.
00:02:12.120 --> 00:02:17.760
On the right-hand side, 13.9 minus three is equal to 10.9.
00:02:18.400 --> 00:02:21.200
Therefore, our value for 𝑥 is 10.9.
00:02:23.360 --> 00:02:29.000
We can check this answer by substituting 10.9 back into the initial equation.
00:02:30.520 --> 00:02:35.680
We were told to add three to our number 𝑥 and then divide the answer by five.
00:02:37.480 --> 00:02:43.440
10.9 plus three divided by five is equal to 2.78.
00:02:43.920 --> 00:02:46.520
Therefore, our value for 𝑥 is correct.
00:02:48.680 --> 00:02:51.280
We now need to deal with the second part of the question.
00:02:52.120 --> 00:02:58.600
We need to calculate the final answer when we add five to 𝑥 and then divide by three.
00:03:00.320 --> 00:03:03.520
Adding five to 𝑥 would give us 𝑥 plus five.
00:03:05.280 --> 00:03:07.800
We then need to divide this answer by three.
00:03:09.680 --> 00:03:12.360
We know that our value for 𝑥 is 10.9.
00:03:12.840 --> 00:03:15.840
So we need to substitute this into the expression.
00:03:17.560 --> 00:03:22.360
This gives us 10.9 plus five divided by three.
00:03:23.760 --> 00:03:27.320
10.9 plus five is equal to 15.9.
00:03:29.160 --> 00:03:32.640
Dividing this by three gives us 5.3.
00:03:34.360 --> 00:03:41.320
The final answer when we add five to 𝑥 and then divide by three is 5.3.