p = 5/7
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First, we can divide both sides of the equation by -3:
-3(9-7p) = -12
9-7p = 4
Now combine the constants by moving the 9 to the right side of the equation. To do this, subtract 9 from both sides:
-7p = -5
Finally, divide both sides by -7 to isolate the variable, p.
p = -5/-7
A negative divided by a negative is a positive number so the answer is:
p = 5/7