a. The image shows that the weight of two k's equals 18. You can write that as k+k=18. In that equation there are two k's so 2 becomes the coefficient of k, making the equation 2k=18
b. To figure out what k equals you need to do the inverse operation. 2k means 2×k, so the inverse operation would be to divide 18 by 2. To check the answer plug 9 back in as k. 2×9=18
