Write an equation system based on the problem "Agatha is five times older than her son, Bob" could be written as: a = 5b.......(first equation) "Three years ago, she was nine times older" could be written as: a - 3 = 9(b - 3)......(second equation)
Solve the equation system To find the value of b, substitute 5b as a to the second equation a - 3 = 9(b - 3) 5b - 3 = 9(b - 3) 5b - 3 = 9b - 27 5b - 9b = -27 + 3 -4b = -24 b = -24/-4 b = 6 Her son, Bob, is 6 years old
To find Agatha's age, substitute the value of b to the first equation a = 5b a = 5 × 6 a = 30 Agatha is 30 years old
