Answer
m=15
Work Step by Step
The single hash marks mean the segments are congruent, so the measures are equal.
$3m+5=4m-10$
subtract 3m from each side
$3m+5-3m=4m-10-3m$
combine like terms
$5=m-10$
add 10 to each side
$5+10=m-10+10$
simplify
$15=m$
