Is the relation (3,-8) (-9 1) (3 2) (-4 1) (-11 -2) and (1,1) (2,0) (3,1) (4,3) (0,2) a function?

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!