A machine heats up a single point by shining several lasers at it. The
equations y = x + 1 and y = -x + 7
describe two of the laser beams. Graph
both of these lines to find the coordinates
of the heated point.

here is a big fat

secant-secant formula:

(whole secant) x (external part) =           (whole secant) x (external part)

(8+y-2) *8=                                           (y+4+6) *6

(y+6)*8 = (y+10) *6

distribute

8y+48 = 6y +60

subtract 6y from each side

2y +48 = 60

subtract 48 from each side

2y = 12

divide by 2

y = 6

sv =     (y+4+6)

sv   = 6+4+6

sv = 16