Question 413165
"susan is twice as old as her brother. five years ago susan was 3 times as old as her brother. find her age"


x = brother's age now
2x = Susan's age now


x - 5 = brother's age 5 years ago
2x - 5 = Susan's age 5 years ago


2x - 5 = 3(x - 5) {five years ago susan was 3 times as old as her brother}
2x - 5 = 3x - 15 {used distributive property}
2x + 10 = 3x {added 15 to both sides}
x = 10 {subtracted 2x from both sides}
2x = 20 {Susan's age now}


Susan is 20 now
<a href = "http://www.algebrahouse.com/" target = "_blank">www.algebrahouse.com</a>