J's answer to Vivi's Primary 5 Maths Whole Numbers Singapore question.
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Ratio method
At first , John : Bervyn = 2 : 1
After, John : Bervyn = 8 : 1
Now, John didn't spend any money. So his money remained at the same amount. We change the first ratio such that the units for John's money are the same for both ratios.
At first , John : Bervyn = 2 : 1 = 8 : 4
So we can see that John had 8 units at first and Bervyn had 4 units at first. She spent 3 units and was left with one unit.
3 units = $23.10
1 unit = $23.10 ÷ 3 = $7.70
John has 8 units at first, so 8 units = $7.70 x 8 = $61.60
At first , John : Bervyn = 2 : 1
After, John : Bervyn = 8 : 1
Now, John didn't spend any money. So his money remained at the same amount. We change the first ratio such that the units for John's money are the same for both ratios.
At first , John : Bervyn = 2 : 1 = 8 : 4
So we can see that John had 8 units at first and Bervyn had 4 units at first. She spent 3 units and was left with one unit.
3 units = $23.10
1 unit = $23.10 ÷ 3 = $7.70
John has 8 units at first, so 8 units = $7.70 x 8 = $61.60
Date Posted:
4 years ago
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