Answer:
The mistake they made was that they subtracted
from
and got
. Instead of subtracting, they should have added it.
Explanation:
Given:

We can combine the system of equations into a single equation:

From this step, we can conclude that the answer for part b is incorrect. The mistake they made was that they subtracted
from
and got 0y. Instead of subtracting, they should have added it.
We can continue solving the system of equations by writing y in terms of x.

now substitute this into the single equation:

Since we now know that
, we can substitute this into the equation we made for y.

The solution for the system of equations is
and
.