Answer:
4
Step-by-step explanation:
We know the other side of the rectangle is 18.
So 18=10+2x
subtract 10
8=2x
divide by 2
x=4
[tex]Hello\\10+2x=18\\10+2x-10=18-10=8\\2x=8\\x=\dfrac{8}{2}=4\\\end{aligned}\\ \boxed{\sf \ x = 4 \ }[/tex]
