two people aged 15 and 50. At some point during their lives, the elder will be three times the age of the younger. Write an equation which models how old in years each will be when the elder will be three times as old as the younger person.
50 + x = elder's future age
15 + x = younger persons future age
50 + x = 3(15 + x)
50 + x = 45 + 3x
2x = 5
x = 2.5 yrs
50 + x = 50 + 2.5 = 52.5 yrs
15 + x = 15 + 2.5 = 17.5 yrs
3 * 17.5 = 52.5