Answer:

Explanation:
-
Subtracting a negative is the same as adding a positive. So I would change the form to addition.
+
Now to add, we need a common denominator. Let's us 27
=
We multiple the numerator and denominator (top and bottom) by 3 to make an equivalent fraction.
+
the bottom number stays the same and we add the top numbers
-15 + 7 = -8
