Solve the system by substitution. check your solution. a - 1.2b = -3 0.2b + 0.6a = 12 a. (15, 15) c. (13, 12) b. (10, 12) d. (7, 9)

a.  (15, 15)

Step-by-step 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

the correct answers i think are b. and d.

give me brainliest if it is correct!

- (2, -7)

- lines r and s and lines t and u must be parallel