For the first part, when we are multiplying a number of two different powers (here being 7 and 5), we must add the powers in order to simplify the expression. So here x7 * x5 = x(7+5) = x12, which is the final answer as 7 + 5 = 12.For the second part, when we have a number raised to a certain power and then raised again to another power (here being -2 and -3 respectively), we must multiply the powers in order to simplify the expression. So here (x-2)-3 = x(-2*-3)= x6, which is the final answer as -2 * -3 = 6.