100 adults and 80 children
sum the parts of the ratio 5 + 4 = 9 parts
divide 180 by 9 to find 1 part of the ratio
[tex]\frac{180}{9}[/tex] = 20 ← 1 part of the ratio
5 parts = 5 × 20 = 100 ← number of adults
4 parts = 4 × 20 = 80 ← number of children
