Peter R. answered 10/04/22
Experienced Instructor in Prealgebra, Algebra I and II, SAT/ACT Math.
x = smaller; y = larger (y>x)
y = x + 20
Four times is larger is 4y; 70 more than five times the smaller is 5x + 70
Set them equal: 4y = 5x + 70
Substitute for y: 4(x + 20) = 5x + 70
Distributive rule: 4x + 80 = 5x + 70
10 = x, then y = 30
Check: 4(30) = 5(10) + 70 (OK, but this assumes the initial equations were set up correctly!)