When there is a midpoint in a line segment, the two segments that are then produced have to be equal. So that means that because E is a midpoint of DF, DE=EF. Set up the equation. DE=EF 2x+4=3x+1 Then solve for x. x=3 Then plug it back in the equation to find DE and EF. DE=2x+4=2(3)+4=10 Because DE=EF then EF is also 10. DF is made from the addition of DE and EF so DF is twice EF. DF= 20