Answer:

Step-by-step explanation:
we know that
The <u><em>Midpoint Theorem</em></u> states that the segment joining two sides of a triangle at the midpoints of those sides is parallel to the third side and is half the length of the third side.
so
In this problem

solve for x
Multiply by 2 both sides

subtract 2x both sides


Adds 1 both sides

60-3d + 20-6 =4d
74-3d =4d
-3d =4d -74
-7d = -74
D=74/7
Therefore, Sandy has 276 football cards.
Hi this is the graph from desmos!