How do I solve this

Answer:
DF = 5
m∠B = 100°
Step-by-step explanation:
It is assumed that ΔABC ≅ ΔDEF
So at this point, all of the measurements that is in one Δ, it also shares the measurements to the other Δ.
AC ≅ DF
DF = 5
AC = 5
m∠B ≅ m∠E
m∠E = 100°
m∠B = 100°