Question 182290
<u>First Equation</u>
"The sum of two numbers is -16":
<code>x + y = -16</code>
<br>
<u>Second Equation</u>
"Their difference is 8":
<code>x - y = 8</code>
<br>
To solve by substitution, we take one equation and solve for one of the numbers (in terms of the other) -- let's solve the second equation for x (in terms of y).  To do this we add "y" to both sides:
<code>
x - y (+ y) = 8 (+ y)
x = 8 + y
</code>
<br>
Next we substitute "8 + y" into the first equation, for "x" and solve for "y":
<code>
(8 + y) + y = -16
8 + 2y = -16
2y = -24
<b>y = -12</b>
</code>
<br>
Now that we know y is -12, we can substitute that value into either equation to find x -- let's substitute it into the first equation and solve for "x":
<code>
x + (-12) = -16
<b>x = -4</b>
</code>
<br>
So our two numbers are <code><b>-4</b></code> and <code><b>-12</b></code>.