I got 20.89, and nearest to the whole number would be 20.
Answer:
The answer is the length of time in one time interval
the line that is parallel will be y = 1/2x
It bisects so DE=EF
DE=5y
EF=13y-8
so
5y=13y-8
minus 13y both sides
-8y=-8
divide both sides by -8
y=1
DE=5y=5(1)=5
DE=EF=5
DF=DE+EF=5+5=10
DE=5
EF=5
DF=10