Help me please?? GEOMETRY

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!

Solve the system of equations y= 3/2 - 1, -x+ y =-3

Ab and bc form a right angle at point b. if a= (-3,-1) and b= (4,4) what is the equation of bc?