Answer:
EF = 58
Step-by-step explanation:
Find the diagram of the question attached.
According to the addition postulate;
DE+EF = DF
Given
DE = 47
EF = 3x+10
DF = 9x-39
Substitute into the addition postulate formula and get x
47+3x+10= 9x-39
Collect like terms
3x-9x = -39-10-47
-6x = -96
x = -96/-6
x = 16
Next is to evaluate EF:
EF = 3x+10
EF = 3(16)+10
EF = 48+10
EF = 58
Hence the measure of EF is 58
