let the smaller number be x
let the larger number be y
According to Question-
x + y = 2y - 4
→ x - y = -4 ...1
if larger number is decreased by 1/3 we get equation -
x + y/3 = -20
→ 3x + y = -60 ...2
adding equation 1 and 2, we get:
4x = -64
→ x = -16
→ y = -60 - 3(-16)
→ y = -60 + 48
→ y = -12