Answer
$x=21$
Work Step by Step
$2x+5=7x-100$ $\longrightarrow$addition property
$2x+5-2x+100=7x-100-2x+100$ $\longrightarrow$ combine like terms
$105=5x$ $\longrightarrow$multiplication property
$105\div5=5x\div5$ $\longrightarrow$simplify
$21=x$