PSLE
Lucy and Barbara each had a plate of dough of the same mass for making sandwiches. The same mass of dough was used for each sandwich. Lucy made 35 sandwiches and had 450 g of dough left. Barbara made 17 sandwiches and had 1.17 kg of dough left.

1. What was the mass of dough needed for each sandwich?
2. With the remaining dough from both girls, how many more such sandwiches can be made at most? 

(a)
Difference between the number of sandwiches made by Lucy and Barbara
= 35 - 17
= 18

1 kg = 1000 g
1.17 kg = 1.17 x 1000 = 1170 g

Difference between the remaining dough left by Barbara and Lucy
= 1170 - 450
= 720 g

Mass of 18 sandwiches = 720 g

Mass of 1 sandwich
= 720 ÷ 18
= 40 g

(b)
Total remaining dough left
= 1170 + 450
= 1620 g

Sets of 40 g
= 1620 ÷ 40
= 40 r 20

Number of sandwiches = 40

Answer(s): (a) 40 g; (b) 40