find the value of a so that the points A(6, 2a) and B(-a, -2) lie on a line having slope 7.
Slope = (y1-y2)/(x1-x2)
7 = (2a- -2)/(6 - -a)
7 = ( 2a+2)/(6+a) solve for 'a'
7 (6+a) = 2a+2 you should be able to take it from here !
