Answer: Wendy used 8 pounds and 7 ounces of potatoes for the potato salad
There are 3 ways of solving a simultaneous problem, substitution method, elimination method and Gauss-Jordan method. I'm gonna use the substitution method since it's easier and i think it would suit your level more.
First let's try solving for y since it's easier to start with.
Firstly we have to find an equation for x:

Great, now we can use the substitution method to find the value of y using the first equation:

Now we know that y=1 we can solve the first equation we made:

And the answer is 
Double check:

And that's our final answer! (4,1)
The answer is definitely not 7.777777
P is less than or equal to (<) 110-52 you want to use the < sign with a line under it. The minus 52 is because he has already thrown 52 out of his 110 and P is how many pitches he is alloted