Someone help I never divided with decimals befor

Given abcd ac=38 and ae=3x+4 find the value of 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!

What is the range? can’t seem to find it out