This question is based on parallel lines proportionality that states if three or more lines intersect two traversals, then they cut the traversals proportionally.
In this case, the formula becomes:





The value of x = 10
To find the proportions or DE and EF,
DE = 2x = 2*10=20
EF = 3x-5 = 30-5 = 25
If we find DE/EF, it becomes 20/25 or 4/5