Answer:
y = 9.54
and, x = 0.08
Step-by-step explanation:
Given that
x - 2y = -19 .......................(1)
3x + 5y = 48 ...............(2)
Based on the above information
Multiply by 3 in equation 1
So,
3x - 6y = -57
3x + 5y = 48
- - -
-11y = -105
y = 9.54
So, the x would be
x - 2(9.54) = -19
x - 19.08 = -19
x = -19 + 19.08
x = 0.08
Im not sure if im correct but I think the answer is 82 hours.
Let's look at the corresponding ratios:

And we see that the three aren't equal.
Hence, $\Delta ABC$ and $\Delta EDC$ are not similar.
Ok so we start with 80 books and remove 50% so 40
2/5 of 40 is 16
16 books