Question 890222
let x be lisa's age and y be her mother's age, then
x +7 = y /2
x -3 = y /3
solve the first equation for x
first multiply both sides of = by 2
2x +14 = y
2x = y -14
x =  y/2 -7
substitute for x in second equation
y/2 -7 -3 = y / 3
multiply both sides of = by 6
3y -60 = 2y
y = 60
Lisa's mother is 60 years old