19x+(1/2)ax=x+9 solve for x
19x + ¹/₂ax = x + 9 - x - x 18x + ¹/₂ax = 9x(18) + x(¹/₂a) = 9 x(18 + ¹/₂a) = 9 18 + ¹/₂a 18 + ¹/₂a x = 9/(18 + ¹/₂a)