Zilani gave 20% of his marbles to Minhaz, and 20% of the rest of marbles to Salman. If he now has 320 marbles, how many did he have originally?

Question: Zilani gave 20% of his marbles to Minhaz, and 20% of the rest of marbles to Salman. If he now has 320 marbles, how many did he have originally?

Solution:
Let original number of marbles = x
After giving 20% to Minhaz,
∴ Remaining = 80% of x
= (80/100) of x
= 0.8x

After giving 20% of the remainder to Salman,
∴ Remaining = 80% of 0.8x
= (80/100) × 0.8x
= 0.64x

Given,
0.64x = 320
⇒ x = 320/0.64
∴ x = 500

∴ The original number of marbles is 500.