Solve by subsitution y equals 8x plus 15 5x-3y equals 12?

Answer 1

y = 8x + 15
5x - 3y = 12

Substitute 8x + 15 for y in the second equation:

5x - 3y = 12
5x - 3(8x + 15) = 12
5x - 24x - 45 = 12 add 45 to both sides:
-19x = 57 divide by -19 to both sides:
x = -57/19

Substitute -57/19 for x in the first equation:

y = 8x + 15
y = 8(-57/19) + 15
y = -456/19 + 15
y = [-456 + (15)(19)]/19
y = (-456 + 285)/19
y = -171/19

The solution is x = -57/19 and y = -171/19