Kim, Betty, and Sarah are cousins. Kim is 4 times as old as Sarah and Betty is 3 years older than Kim. The sum of all their ages is 75. Find the ages of each of the girls.
Let Sarah's age = A
Let Kim's age = 4A
Let Betty's age = 4A + 3
So
A + 4A + 4A + 3 = 75
9A + 3 = 75 subtract 3 from both sides
9A = 72 divide both sides by 9
A = 8 = Sarah's age
4(A) = 4(8) = 32 = Kim's age
4(A) + 3 = 32 + 3 = 35 = Betty's age
