PSLE
Ivory and Mary made some vanilla sandwiches and blueberry sandwiches. Ivory made 31 more vanilla sandwiches than blueberry sandwiches. Mary made 175 more blueberry sandwiches than vanilla sandwiches. The total number of vanilla sandwiches made up 32% of the total number of sandwiches they made. How many vanilla sandwiches did they make altogether?

Number of blueberry sandwiches		Number of vanilla sandwiches
68%		32%
Ivory	Mary	Ivory	Mary
1 u	1 p + 175	1 u + 31	1 p

Ivory
Number of blueberry sandwiches = 1 u
Number of vanilla sandwiches = 1 u + 31

Mary
Number of vanilla sandwiches = 1 p
Number of blueberry sandwiches = 1 p + 175

Number of blueberry sandwiches in percent
= 100% - 32%
= 68%

1 u + 31 + 1 p = 32% --- (1)
1 u + 1 p + 175 = 68% --- (2)

(2) - (1)
68% - 32% = 175 - 31
36% = 144

1% = 144 ÷ 36 = 4

Number of vanilla sandwiches that they made altogether
= 32%
= 32 x 4
= 128

Answer(s): 128