so permiter=masure of all sides added together
so sides are(3x+2), (2x+5), and (4x)
so (3x+2)+(2x+5)+(4x)
use associative property
a+(b+c)=(a+b)+c so
(3x+2)+(2x+5)+(4x)=3x+2+2x+5+4x
group like terms becasue can move numbers around
(3x+2x+4x)+(2+5)
add like terms
(9x)+(7)
9x+7
he will use 9x+7=perimiter