2x + 3y = 630
x + y = 245 then you want to get rid of x so in the second equation × by -2 and get -2x -2y =-490 subtract this equation from the first to get y=$140 substitute 140 in for y and get x= $105 and 2x=210 and 3y=420 210 +420=630
So anytime we have a slope and want to find the slope of a perpendicular line, we just have to remember a perpendicular line's slope is the negative reciprocal (reciprocal means flip the fraction). So if we had a slope of 3/4, the slope perpendicular to it would be - 4/3.
First we need to find our slope, to do this we take the change in y over the change in x like so:
(15-12)/(4-7) = - 3/4
The slope perpendicular to this is 4/3.
