So,
Let's translate this into mathematical form.
x - y = 9
x + 2y = 27
Elimination by Addition
Divide both sides of the second equation by 2
[tex] \frac{1}{2}x + y = 13 \frac{1}{2} [/tex]
Add the two equations together
[tex] \frac{3}{2} x = \frac{45}{2} [/tex]
Multiply both sides by [tex] \frac{2}{3} [/tex]
[tex]x = \frac{90}{6} \ or \ 15[/tex]
Substitute
15 - y = 9
Subtract 15 from both sides
-y = -6
y = 6
Substitute
15 - 6 = 9
9 = 9 This checks.
15 + 2(6) = 27
Distribute
15 + 12 = 27
27 = 27 This also checks.
S = {(15,6)}
