What is the solution of the system?
use the substitution method.
{y+7=3x
{6x−2y=12
a) (14, 12)
b) (12, 14)
c)there is no solution.
d)there are an infinite number of solutions.

Y + 7 = 3xy = 3x - 7
so we sub in 3x - 7 for y in the other equation

6x - 2y = 12
6x - 2(3x - 7) = 12
6x - 6x + 14 = 12
6x - 6x = 12 - 14
0 = -2 (incorrect)no solution

Little tip :
if ur answer comes out with unequal amounts such as : 1 = 4, or 2 = 3, or 0 = -2...then there will be no solutions.
if ur answer comes out with equal amounts such as : 2 = 2, 3 = 3,0 = 0then there will be infinite solutions.
if ur answer comes out with a variable equaling something...y = 4, x = 2, then there is 1 solution