Answer:
-25
Step-by-step explanation:
First, write an equation to represent the situation. To get -87, a number (lets say x) is first tripled, and then 12 is subtracted from the result.
So: -87 = 3x - 12
Then, solve for x by first adding 12 to both sides:
-87 = 3x - 12 ----> -75 = 3x
Finally, divide both sides by 3 to get x by itself:
-75 = 3x ----> -25 = x