Algebra
posted by Anonymous on .
The bongo family has three children, including a pair of twins. The third child is 3 years younger then the twins. The sum of the three ages is 42. How old is each child?

a = age of the twins
b = age of the third child
b = a  3
a + a + b = 42
2 a + b = 42
2 a + a  3 = 42
3 a  3 = 42
3 a = 42 + 3
3 a = 45 Divide both sides by 3
a = 45 / 3
a = 15
b = 15  3
b = 12 
the first of two films lasted 9 minutes less than twice as long as the second. the combined length of the two films plus a 5minute break between them was 260 minutes. how long was the first film?

x + 2x  9 + 5 = 260
3x  4 = 260
3x = 264
x = 88