80/32 -> 10/4 -> 5/2 (divided by 8, then by 2)
24/21 -> 8/7 (divided by 3)
2/9 to 7/6 -> 4/21
Find least common denominator (18), and fractions/ratio become 4/18 to 21/18. Multiply both times 18 to eliminate the denominators = 4 to 21 = 4/21
4 1/2 to 2 1/2 -> 9/2 to 5/2 -> 9/5
Convert mixed numbers to fractions:
9/2 to 5/2
Multiply both by 2 to eliminate the denominators, and the ratio is 9 to 5 = 9/5
