You must perform a subtraction between the result of two multiplications. In fact, since multiplications have a higher priority than subtraction, you must perform them first. Also, remember that a positive times a negative is a negative.
So, you must perform the operations in this order:
[tex] [-6\cdot 7]-[6\cdot(-2)] = [-42]-[-12] = -42+12 = -30 [/tex]
