Evaluate the function f(x) = 4•7^x (for x = -1 & x = 2) show your work. in dire need of w/ this one!

Thomas works for a company that occupies a large campus every workday he orders a cup of coffee on campus and the $1.50 cost is automatically deducted from his paycheck. if thomas visits the coffee shop 13 times what will the net change in his paycheck be