Answer:
DF = 7.5
Step-by-step explanation:
Since the 3 sides are congruent, then
EF = DE , that is
4.5m - 42 = 1.5m - 9 ( subtract 1.5m from both sides )
3m - 42 = - 9 ( add 42 to both sides )
3m = 33 ( divide both sides by 3 )
m = 11
Thus
DE = 1.5m - 9 = 1.5(11) - 9 = 16.5 - 9 = 7.5
Then
DF = 7.5
