Question 56288
P(x) = 2 ( l + w )
l = 3x+9
w = 2x-5
x = 4
DO NOT plug x in yet.  Even though this is a simple number, sometimes you will have a fraction or a decimal to plug in, and it is easier to combine like terms and multiply once, than to multiply several times and then add.
{{{ P(x) = 2 ( 3x + 9 + 2x -5 ) }}}
First combine like terms
{{{ P(x) = 2 ( 5x + 4 ) }}}
Disxribute 
{{{ P(x) = 10x + 8 }}}
NOW plug in the x
{{{ P(4) = 10(4) + 8 }}}
Multiply
{{{ P(4) = 40 + 8 }}}
{{{ P(4) = 48 }}}