Answer:
f= -5
Explanation:
-12=f-7 than u subtract the f to the other side giving you -f-12=-7 than you add the 12 to the -7 giving you 5 but than you have -f=5 and you need f to be bye it self and it's not bye it self because, it have the negative with it so you need to divide -1 into 5 giving you f= -5