Say he invested $x in A. So amount invested in B is 5000 - x. Total earned from A = 1.2 * x ---> every $ becomes $1.2 Total earned from B = 1.05 * (5000 - x) ----> every $ becomes $1.05 Total =i.e. Simplifying: or So, amount invested in A is $2800, and that invested in B is $2200. Check: 2800 becomes 2800 * 1.2 = 3360 2200 becomes 2200 * 1.05 = 2310 Total = 3360 + 2310 = 5670. Correct! Hope this is clear :)