Answer :
The formula of a perimeter of a rectangle:
[tex]P=2(l+w)[/tex]
We have:
[tex]P=120\ in\\\\l=w+10[/tex]
Substitute
[tex]2(w+10+w)=120\\\\2(2w+10)=120\ \ \ \ |:2\\\\2w+10=60\ \ \ \ |-10\\\\2w=50\ \ \ \ |:2\\\\w=25\\\\l=25+10=35[/tex]
The formula of a perimeter of a rectangle:
[tex]P=2(l+w)[/tex]
We have:
[tex]P=120\ in\\\\l=w+10[/tex]
Substitute
[tex]2(w+10+w)=120\\\\2(2w+10)=120\ \ \ \ |:2\\\\2w+10=60\ \ \ \ |-10\\\\2w=50\ \ \ \ |:2\\\\w=25\\\\l=25+10=35[/tex]