WEBVTT
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A bag contains blue, red, green, and yellow counters only.
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In total, there are 528 counters in the bag.
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One-third of the counters are green.
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67 of the counters are red.
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115 of the counters are blue.
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Work out how many of the counters are yellow.
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So we’re told in the question that the bag only contains blue, red, green, and yellow counters.
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And we’re also told that the total number of counters in the bag is 528.
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This means that the numbers of blue, red, green, and yellow counters must sum to 528.
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We’re also told in the question that 67 of the counters are red and 115 of the counters are blue.
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So we can substitute these values into the equation that we’ve written.
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We have 115 plus 67 plus the number of green counters plus the number of yellow counters is equal to 528.
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The other piece of information we’re given in the question is that one-third of the counters are green.
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To find one-third of a number, we just divide it by three.
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So we divide the total number of counters, which is 528, by three, giving 176.
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We can perform this division on a calculator if it’s available or we can use a short division method.
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Now we’ve worked out that the number of green counters in the bag is 176, so we can substitute this value into our equation.
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We don’t know what the number of yellow counters in the bag is, but this is what we’re looking to work out.
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And we now have all the information to enable us to do so.
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We just need to solve the equation that we’ve got.
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115, 67, and 176 sum to 358.
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So our equation becomes 358 plus 𝑦, the number of yellow counters, is equal to 528.
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To solve this equation, we just need to subtract 358 from each side.
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And it gives 𝑦 is equal to 170.
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This is the number of yellow counters in the bag.