Question 661568
x = mark
y = danielle
x  = y - 60
4(x - 3) = y - 3
Substitution
4(y-60)-3 = y - 3
Distribute the 4
4y - 240 - 3 = y - 3
Combine like terms
3y = 240
y = 80
x=80-60=20 years old for Mark