ken spend 1/5 of his money on a dictionary. he gives $21 to his brother and has 1/2 of his money left. how much money does ken have left?

Answer 1

if he starts out with x, we have

(x - x/5) - 21 = x/2
x = 70

check:
1/5 of 70 is 14

70-14-21 = 35, which is 1/2 of 70