Question 122154
 Let name x the number of groups that he bought (each group has 3 apples)

so she buy x groups (each group cost 35 cents) so she spend 35x cents

then she has 3x apples and he sold each of them at 25 cents (each apple)

she sold 90% of the apples so he earned 3(0,9)25x cents

so the profit is  3(0,9)25x-35x =67,5x-35x=650 so 32,5x=650 so x=20

then he buy 60 apples and she did not sell 10% (6 apples)