Question

If DE = 4x + 10, EF = 2x-1, and DF = 9x-15, find DF

Answer 1

Hello,
We have that:
(4x+10)+(2x-1)=9x-15

We solve the equation:
4x+10+2x-1=9x-15;
6x+9=9x-15;
6x-9x=-15-9;
-3x=-24;
3x=24;

from which
x=24:3=8

Then:
DF=9x-15=(9×8)-15=72-15=57

bye :-)