The answer is : p = -4
the following are the steps to solve it::
13 - 3p = -5 (3 + 2p)
calculate the area of the right hand first by multiplying the number 5 by the number in brackets
13 - 3p = -15 - 10p
move everything that contains p to the left side
13 - 3p + 10p = - 15
count all containing p
13 + 7p = -15
move the ones that don't contain p to the right
7p = -15 - 13
count on the right side
7p = - 28
p = -4