Ayesha has only ₹ 5 and ₹ 10 coins with her. If the total number of coins she has is 25 and the amount of money with her is ₹ 160, then the number of ₹ 5 and ₹ 10 coins with her are

Let x = number of ₹5 coins, y = number of ₹10 coins. Then x + y = 25 and 5x + 10y = 160. From the first equation, x = 25 - y. Substituting: 5(25-y) + 10y = 160, which gives 125 - 5y + 10y = 160, so 5y = 35, y = 7. Then x = 25 - 7 = 18. So there are 18 coins of ₹5 and 7 coins of ₹10. Verification: 18×5 + 7×10 = 90 + 70 = 160. ✓