<h2>
Answer:</h2>
Two are the keys of this problem. First, a parallelogram is a quadrilateral (a polygon with four sides) where both pairs of opposite sides are parallel. Second, for every parallelogram its diagonals bisect each other, that is, each diagonal is divided into two equal parts. So, from the figure it is true that:
Since 
Then:
Answer:
40
Step-by-step explanation:
3x + 7 = 5x - 15
2x = 22
x = 11
QC = 51 - x = 51 - 11 = 40
Replace the informations you don't know with letters.
x = number of bags
y = number of sandwiches
7x + 3y = 22
3x + y = 8
Then solve the equations.
First, isolate the y in the second one like this :
y = 8 - 3x
then replace the y in the first equation with its worth from the second equation :
7x + 3(8 - 3x) = 22
solve for x, then replace the value in the equations to get the value of y
Since both terms are perfect squares, factor using the difference of squares formula.
a^2- b^2= (a+b) (a-b) where a=x+2y and b=2z
(x+2y+2z) (x+2y-2z)
