Question 546536
Ling x years
Mei --- y years

x+y=44...................(1)

4 years ago 
ling = x-4
Mei = y-4

(x-4)=3(y-4)
x-4 = 3y-12
x-3y=-8...................(2)

Multiply (1) by 3
3x+3y=132

add it to (2)
4x=124
/4
x=31 lings age
Mei's age = 44-31=13