Let's solve your system by substitution.
x+y=8;x−y=4
Step: Solvex+y=8for x:
x+y=8
x+y+−y=8+−y(Add -y to both sides)
x=−y+8
Step: Substitute−y+8forxinx−y=4:
x−y=4
−y+8−y=4
−2y+8=4(Simplify both sides of the equation)
−2y+8+−8=4+−8(Add -8 to both sides)
−2y=−4
−2y/−2=−4/−2 (Divide both sides by -2)
y=2
Step: Substitute2foryinx=−y+8:
x=−y+8
x=−2+8
x=6(Simplify both sides of the equation)
Answer:
x=6 and y=2