Answer:
when (-1, -4) is substituted into the first equation it's true
when (-1, -4) is substituted into the second equation it's true
the ordered pair (-1, -4) is a solution to the systems of equation
Step-by-step explanation:
original equation
x-y=3
multiply both sides by 7
7x-7y = 21
add 7y to both sides
7x=7y + 21
substitute into second equation
(7y+21)-y=-3
simplify
6y+21=-3
subtract 21 from both sides
6y=-24
y=-4
substitute y into original equation
x-(-4) = 3
cancel out negative signs
x+4=3
subtract -4 from both sides
x=-1
