8(r-2)=40 what is the answer to this equation

The answer is r=-3. You use the distributive property which is basically multiplying -8 with all the numbers inside the parenthesis. So -8 x r and -8 x -2. This results to -8r+16=40 (Two negative numbers multiplied together will form a positive number). We use inverse operations to subtract 16 from both sides. 16-16 is 0 and 40-16 is 24. So we are left with -8r=24. We want to be left with only r, so we once again use inverse operations to divide -8 from both sides. -8/-8 is 1, and 24/-8 is -3. So we end up with r=-3. Hope this helped :]