Are the expressions (5+5+5+5) + (x+x+x+x) and 4(5+x) equivalent? If so, write another expression that is equivalent to both of them. If not, explain why not.

Yes, they are equivalent. Something that is not equivalent is 5(9+10x)

to find the perimeter of the rectangle this is the expression:

x-9+x-9+3x-4+3x-4=138

if we simplify it:

8x-26=138

remember, 138 is what it all adds up to

the length is 11.5cm

the width is 57.5cm

the area is 661.25cm^2

the answers might not be correct use at own risk