Question 1005275
Hi there,
Sushil is now 4times as old as sunil.
Sush = 4Sun
Five years ago sushil was 7 times as 
old as sunil was then.
Sush - 5 = 7(Sun - 5)
Sush - 5 = 7Sun - 35
Replace Sush with 4Sun from top equation
4Sun - 5 = 7Sun - 35
Collect like terms
4Sun - 7Sun = -35 + 5
-3Sun = -30
Multiply both sides by -1
3Sun = 30
Sun = 10
Sunhil is currently 10 years old
Sushil is currently 40 years old.
Hope this helps :-)