Answer: 32:40
step 1: add the two sides of the ratio 4+5=9
step 2: divide 72 by 9
72/9=8
step 3: solve either side of the ratio by multiplying by answer to step 2
so 8 × 4=32 and 5 × 8=40
step 4: check answer by adding the two sides of the ratio 32 + 40 = 72
