I'm confused on the equations. am i supposed to do two of them? 27.50=4p+2d and 18.25=2p+3d?

(1)27.50=4p+2d
(2)18.25=2p+3d
lets multiple second equation by -2
-2x(18.25=2p+3d)= -36.5=-4p-6d (3)
Lets sum 1 and 3 ==.>
27.50=4p+2d +
-36.5=-4p-6d

now we have  -9=-4d d=9/4
if you sub this in any of the equations you will get P
27.50=4p+2(9/4)
27.5=4P+18/4    27.5-18/4=4p     23=4P

P=23/4