College

Which could be the resulting equation when elimination is used to solve the given system of equations?

[tex]
\[
\begin{cases}
5a + 5b = 25 \\
-5a + 5b = 35
\end{cases}
\]
[/tex]

A. [tex]10a = 60[/tex]

B. [tex]10b = 60[/tex]

C. [tex]-10a = 60[/tex]

D. [tex]-10b = 60[/tex]

Answer :

We start with the system of equations:

[tex]$$
\begin{aligned}
5a + 5b &= 25 \quad \text{(1)}\\
-5a + 5b &= 35 \quad \text{(2)}
\end{aligned}
$$[/tex]

Our goal is to eliminate one of the variables by adding the two equations together. Notice that by adding (1) and (2), the [tex]$a$[/tex]-terms cancel out:

[tex]$$
(5a + 5b) + (-5a + 5b) = 25 + 35.
$$[/tex]

Simplify the left-hand side:

[tex]$$
5a - 5a + 5b + 5b = 0 + 10b = 10b.
$$[/tex]

And simplify the right-hand side:

[tex]$$
25 + 35 = 60.
$$[/tex]

Thus, we obtain the equation:

[tex]$$
10b = 60.
$$[/tex]

This is the resulting equation after the elimination step.