Suppose a is directly proportional to b, but inversely proportional to c. If a = 3 when b = 5 and c =9, then what is c when b=3 and a = 4?
a =b/c k where k is proportionality constant
ac/b = k
Sub in the values given
3*9 /5 = 27/5
Sub in the second set of numbers
4c/3 = 27/5
c = 4.05