Scca math help !! i dont understand these two

For questions 1–2, solve each system by graphing on a separate piece of paper. Is (–2, 3) the solution of each system?
1. x + y = 1

x = –2 (1 point)
yes
no
2. y = 2x + 7

x = y – 4 (1 point)
yes
no

For (system) equation 1, since x = -2. substitute this value in x+y=1 to obtain:
y -2 = 1 . therefore y= 3 (hence (-2,3) is a solution)

For (system) equations 2, since x= y-4. substitute this value in y= 2x +7 to obtain:
y= 2y - 8 +7. therefore y =1 and substituting this value back in x = y -4 to obtain x = -3 (hence -2,3 is not a solution.) (-3,1) is the solution