Answer:
60
Step-by-step explanation:
We can use 5·7 = 35 as a common denominator for these fractions. This tells us the fraction of red chairs is 2/5 = 14/35, and the fraction of blue chairs is 3/7 = 15/35. The rest of the (35 -14 -15)/35 = 6/35 chairs are yellow. This means the ratio of chair colors is ...
red : blue : yellow = 14 : 15 : 6
Multiplying this by 4 will give 24 yellow chairs:
4·14 : 4·15 : 4·6 = 56 : 60 : 24 . . . . red : blue : yellow chairs.
60 chairs are blue.
