Answer: 6
Step-by-step explanation:
Given DE, EF and DF, we know that DE and EF make up DF. We add DE and EF and set it equal to DF.
6x+4x=10 [add]
10x=10 [divide both sides by 10]
x=1
Now that we know x=1, we can plug that into DE.
6(1)=6
Now, we know that DE is 6.
