Answer:
The length of DF is 15
Step-by-step explanation:
Since the two lines are equal, which is given by the markings on the triangle, then you can set the two lengths equal and find x.
7x - 13 = 3x + 3
4x - 13 = 3
4x = 16
x = 4
Now that we know x = 4, we can plug into the DF length to find its amount.
DF = 7x - 13
DF = 7(4) - 13
DF = 28 - 13
DF = 15
