There are 3 red fish for every 5 blue fish in an aquarium. a) If there are 30 blue fish, how many red fish are there?
b) If there are 30 red fish, how many blue fish are there?

a) 18 red

b) 50 blue

Step-by-step explanation:

a)

3r = ?        the common multiplier is 6; 3 x 6 = 18

5b    30b

b)

3r = 30        the common multiplier is 10; 5 x 10 = 50

5b      ?

step-by-step explanation:

the triangles are similar. therefore the corresponding sides are in proportion:

              cross multiply

            divide both sides by 32