Yoko paid $420 for some cupcakes and biscuits. The ratio of the boxes of cupcakes to the boxes of biscuits was 3 : 5. Each box of cupcakes cost $5 more than each box of biscuits. She paid $120 more for the cupcakes than the biscuits. What was the price of each box of cupcakes?
(a)
Total amount that the biscuits cost
= (420 - 120) ÷ 2
= 300 ÷ 2
= $150

Total amount that the cupcakes cost
= 150 + 120
= $270

Number of sets of cupcakes = 3
Number of sets of biscuits = 5

Cost of 1 set of cupcakes
= 270 ÷ 3
= $90

Cost of 1 set of biscuits
= 150 ÷ 5
= $30

Amount that 1 set of cupcakes cost more than 1 set of biscuits
= 90 - 30
= $60

Number of boxes of cupcakes in 1 set
= 60 ÷ 5
= 12

Price of each box of cupcakes
= 90 ÷ 12
= $7.50

Answer(s): $7.50