Answer:
a. (15, 15)
Explanation:
We start with those two equations:
1) a - 1.2b = -3
2) 0.2b + 0.6a = 12
We'll begin by modifying equation #1 to isolate a:
a = -3 + 1.2b
Then we'll use this value for a in the second equation:
0.2b + 0.6 (-3 + 1.2b) = 12
0.2b - 1.8 + 0.72b = 12
0.92b = 13.8
b = 15
Then we'll place that value of b in the first equation to find a:
a - 1.2 (15) = -3
a - 18 = -3
a = 15