What is the value of r? justify each step

DF=40

there is a line with three points D is on the first point, E is on the second point and F is on the third point. In between D and E is 3r+6 and in between E and F is 2r+4

DE+EF= DF is blank
3r+6+2r+4=40 is blank
5r +10=40 is blank
54+30 is blank
r=6 is blank

1 Answer
Jim G.
Nov 21, 2017

#r=6#

Explanation:

#DF=DE+EFlarrcolor(blue)"2 segments sum to give line DF"#

#color(white)(DF)=(3r+6)+(2r+4)larrcolor(blue)"length of each segment"#

#"collecting like terms gives"#

#(3r+2r)+(6+4)=5r+10#

#rArr5r+10=40larrcolor(blue)"the length of DF"#

#"subtract 10 from both sides"#

#5rcancel(+10)cancel(-10)=40-10#

#rArr5r=30#

#"divide both sides by 5"#

#(cancel(5) r)/cancel(5)=30/5#

#rArrr=6#

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