Answer:
f= 3
Step-by-step explanation:
-12 = 4f-24
+24. +24
----------------
12 = 4f
/4. /4
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3
-12 = 4(f - 6)
-12/4 = (4(f - 6))/4
-3 = f - 6
-3 + 6 = f - 6 + 6
3 = f