if you try to solve this equation with the (1,5), you lay it out like 5 = 1/4 * 1 - 7. It turns into 5 = 1/4 - 7, because 1 times anything is that same number. Then you have to add 7 to both sides so that it cancels out on the right and you get 12 on the left. So you end up with the equation 12 = 1/4. This equation is not true, so therefore (1,5) is not a solution. Hope this helps :)
