Respuesta :

p = 5 .............................................
this is how= 

first you expand the second equation 
25 + 4p = -18 + -12 + 6p + 9p

then you add the like terms in the second equation:
25 + 4p = -30 + 15p
then this is how=
25+30 = 15p -4p
55=11p

p= 5