Find x please step by step explanation need it

If c(x) = 4x – 2 and d(x) = x2 + 5x, what is (cxd)(x)

Can someone me and plz do the problem

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!