We know the perimeter is the total sum of all sides of the shape, we can use this to form an equation: the perimeter=1st side + 2nd side + 3rd side + 4th side 39a-7=9a+(5a+1)+(17a-6)+4th side.
Collect like terms to get 39a-7=31a-5+4th side
If we move everything but the 4th side over to the left we can solve
C. 8a-2=4th side is the correct answer
I hope this helps you
DF^2+DC^2=FC^2
DF^2+15^2=39^2
DF^2=39^2-15^2
DF^2=24.54
DF=36
Answer:


Step-by-step explanation:
Perimeter of the trapezoid-shaped window = sum of all the sides of the window frame
Thus, the equation to find the unknown side length, x, would be:
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Solve for x

Subtract 14.89 from each side

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Each child can get 2 bags of m&m's and one Hershey's bar. Hope it helps! :)