7 books costs $14, etc. We have points in a line
(7,14)
(8,16)
(9,18)
They're all points on the line y=2x which just means it costs $2 a book. So 1 book costs $2, 2 cost $4, and 3 cost $6. We have three new points:
(1,2)
(2,4)
(3,6)
They're all on the same line, y=2x, just closer to the origin than the first three. We plot a point at x=1, y=2, etc.
Merry Christmas
(x-7)(x-5)=x-7
(x-7)(x-5)-(x-7)=0
(x-7)[(x-5)-1]=0
(x-7)(x-6)=0
x=7 or x=6
Hope this can help.
