Aman gave 5/8 of his money to his wife and spent 2/3 of the remainder. if he has spent 800$, how much did he give to his wife

800 multipliyed be 3/2 gets us 1200. that is the remainder. 3/2s is the recipicle of 2/3, that's how this equation can work, if you multiply a fraction by its recipicle you get 1 and in this case 1200.
now divide 1200 by 3 to get 400, that is 1/8 of his total money since 3/8 divided by 3 is 1/8.
Now multiply 400 by 5 to get 2000 that is 5/8 of his money, what he gave his wife, this works since 1/8 multiplied by 5 is 5/8.