Answer:
a = 9/2
Explanation:
In order for the equation to be true, the value of the scalar multiplier must be ...
15/3 = -10/-2 = 35/7 = 5
So, you're solving ...
(2/3)a + 2 = 5
(2/3)a = 3 . . . . . . subtract 2
a = 9/2 . . . . . . . . multiply by 3/2