The answer is just -18
Walkthrough: The formula for this problem is m= y2 - y1/x2 - x1
x1,y1 is (34,12) and x2,y2 is (32,48) [As it said in the given problem].
Substituting it, your form would be written as
m = 48 - 12 / 32 - 34
let's continue solving it.
m = 36/-2
now divide them both by 2
m = 18/-1
the final written form would be -18
[I took the same Unit Test Btw]