Khalid is now four times as okd as his daughter. Ten years ago,if the sum of their ages was sixty. Find the present age of his daughter?

Answer 1

khalid=k
daughter=d
first statement
k=4d...(1)
second statement
(k-10)+(d-10)=60.
k+d=60+20
k+d=80...(2)
plug 1 into 2 and there you go