The answer is a =2.25 or 9/4.
Work Step by Step
To solve this question by graphically you can graph the left side and then graph the right hand side. so for 8a-12=6 you graph y =8a-12 and then graph y=6. The two graphs will intersect and the x coordinate of the point of intersection would be the value of a as you are plugging a=2.25 in y=8(2.25)-12 which is y=18-12=6.