let

c = the cost of 1 cup

s = the cost of 1 saucer

b = the cost of 1 bowl

2 cups cost the same as 3 saucers

2c = 3s => s = (2/3)c if we replace in

5s = 4b( 5 saucers cost the same as 4 bowls)

4b = 5*(2/3)c

4b = (10/3)c multiply both sides by 3

12b = 10c

12 bowls cost the same as 5 cups.