If x^{2} + y*sqrt{xy} = 10 and y^{2} + x*sqrt{xy} = 20, what is x?

Dakota earned $7.50 in interest in account a and $18.75 in interest in account b after 15 months. if the simple interest rate is 4% for account a and 5% for account b, which account has the greater principal? explain. to make it a little easier, there is an image. good luck!