Last month Taufik spent 1/7 of his salary on transport. He spent 5/8 of his remaining salary and another $20 on food. He had $1357 left in the and How much did he spend on transport?
xport: 1/7, leaving 6/7
food: 5/8 * 6/7 = 15/28, leaving 9/28
so now you know that if his salary was x,
9/28 x - 20 = 1357
Find x, and then get 1/7 x