One side of a triangular garden is x feet long. the other two sides of the garden are both 5 feet less than twice the length of the first side of the garden.
part a: write a simpiflied expression for perimeter, in feet, of the garden.
a fence is placed along the entire perimeter of the triangular garden. the roll of fencing is 40 ft long.
part b: write a simplified expression to show the amount of fencing, in feet, which is left from the roll of fencing.

A:  If the 1st side of the garden is x feet long then the other sides are 2x - 5.  The perimeter is simply the measure of the distance around the triangle, so the length of all three sides added up.  So the equation to find the perimeter (p) would be...

p = x + (2x+5) + (2x+5)
or
p = x + 2(2x+5)

This is actually an equation so the expression to represent perimeter would simply be...

x + 2(2x+5)

B:  Since we know the equation for the perimeter and we know that we have 40 feet of fencing, then the equation to find the left over fencing would just be the length of fencing minus the perimeter...

40 - x + 2(2x+5) = the leftover amount of fencing

so the expression is...

40 - x + 2(2x+5)