how do i do substititions

Question

y=x-1 and  x+y=3.

Answer 1

Substitution method

Given first equation y = x - 1 ---> (1)

Second equation x + y = 3 ---> (2)

From (1) substitute the y  value in (2).

x + x - 1 = 3

2x - 1 = 3

Add 1 to eachside.

2x  = 4

Divide each side by 2.

x  = 2.

Substitute x  value in (1).

y  = 2-1

y  = 1.

Solution x  = 2 and y = 1.