1/5 = 0.2 1/4 = 0.25 0.8x > 0.75(x + 1) 0.8x> 0.75x + 1 - 0.75x 0.05x > 1 ÷ 0.05 x > 20 So because x (their current age) can't equal 20, the smallest value you can have is 21, which is your answer. Let me know if you have any questions, hope this helps :)
