Riaz’s age after 15 years will be 5 times his age five times back, what the present age of Riaz?

Suppose the age of Riz= X
Riaz Age after 15 Years will be 5 times his age 5 years back= X + 15 = 5 (x-5)
X+15 = 5 (x-5)
X+15 = 5X -25
X+15 +25=5X
5X – X =40
4X = 40
X=40/4
X=10