If the height of Rasel is less by 20% than Maruf, the height of Maruf will be greater than that of Rasel by how many percent?

Question: If the height of Rasel is less by 20% than Maruf, the height of Maruf will be greater than that of Rasel by how many percent?

Solution:
Let the height of Maruf is x and height of Rasel is y.
Then, height of Rasel = x - 20% of x
y = x - (20x)/100
⇒ y = x - x/5
⇒ y = (5x - x)/5
⇒ y = 4x/5
∴ x = 5y/4

Now,
height of Maruf - height of Rasel
= 5y/4 - y
= (5y - 4y)/4
= y/4

∴ Height of Suresh will be greater than that of Ramesh by = {(y/4)/y} × 100
= (y/4) × (1/y) × 100
= 25%