4. If DF = 9x - 39, find EF. Help I’m so confused!!!!

Question

asked Nov 23, 2020 49.8k views

2 Answers

Painiyff · Answer 1 · 2020-11-25T20:47:45+0000

Answer:

EF =58

Explanation:

from the illustration,

EF =DF - DE

given that DF =9x-39 , DE =47 EF=3x +10

substitute them into the formula,

3x +10=9x-39 - 47

solving for x

3x +10 =9x -86

grouping like terms

3x - 9x =-86 -10

-6x=-96

dividing through by -6

but EF=3x+10

substitute x=16 into it to get the EF

EF= 3(16)+10

EF=48+10

EF=58

Gijs Brandsma · Answer 2 · 2020-11-30T12:48:10+0000

$\huge\boxed{58}$

First of all, we know that
DE+EF=DF , because these are two segments that make up one larger segment.

Write this as an equation.

DE+EF=DF

47+(3x+10)=9x-39

Remove the parentheses.
47+3x+10=9x-39

Combine the like terms.
3x+57=9x-39

Subtract
from both sides.
-6x+57=-39

Subtract
from both sides.
-6x=-96

Divide both sides by
.
x=16

Now, find
.

3x+10

3(16)+10

Multiply.
48+10

Add.
$\boxed{58}$