Answer:
15
Step-by-step explanation:
The total number of teachers in the school is 100.
The number who teach Science is 60
The who teach humanities is 25.
The number that teach both humanities and Science is 15.
We want to find the number who teach Science but not Humanities.
We obtain this by subtracting the number of teachers who teach both subjects from the number that teach Science.

Therefore 25 teaches science but not Humanities
Answer:
a) x=7
b) x=4
c) x= 1/9
I hope this helps! Do you need more help?
Well.. for the equation x= 3.5, let's take a look at its values

so.. notice.. no matter what "y" is, "x" will always be 3.5,
so is really just a horizontal line, thus, look at the picture below