If you distribute -4 through (5k-7), it equals -20k + 28. Then put on the other -2k on that side of the equals sign and you should have -22k + 28 = -2(9k+5) Then you need to distribute -2 through (9k+5) which equals -18k - 10. You then should have -22k+28=-18k-10. Add 22k to both sides to cancel it out, then you should have 28=4k-10. Add 10 to both sides to get the 4k by itself, which will be 38=4k, then divide both sides by 4 to get k by itself. 38/4 = 19/2. k = 19/2
This is the concept of algebra, the average number of muffins baked by each girl will be given as follows;
Muffins baked by Andrea=h muffins
Muffins baked by Violet =h-8
Average=(Total sum of numbers)/(Number of items)
total sum=h+(h-8)=2h-8
Number of items=2
thus;
average=(2h-8)/2=h-4
the answer in terms of h is (h-4)