Question

18 What is the solution to the system of equations x - y = -1 and x-3y = - 13?

A. (5, 6)
B.
(6,5)
C. (7,8)
D.
(8,7)

Answer 1

Answer is A. ( 5, 6)

Using elimination, subtract EQ.2 from EQ.1
When we subtract, we change the sign of EQ.2 and add

x - y = -1 Equation 1
- (x - 3y = -13) Equation 2

x - y = -1 Equation 1
-x + 3y = 13 Equation 2
__________
2y = 12
Divide both sides by 2 to solve
2/2 y = 12/2
y = 6

Substitute y value of 6 into EQ.1

x -6 = -1
Add 6 to both sides to solve for x
x -6 +6 = -1 +6
Simplify
x = 5

Solution: ( 5, 6 )