yes
remember you can do anything to an equaiton as long as you do it to boh sides
ad try to get unknown to one side
9n-10=4n+10
minus 4n both sides
9n-4n-10=4n-4n+10
5n-10=0+10
add 10
5n+10-10=0+10+10
5n+0=20
5n=20
divide both sies by 5
5n/5=20/5
5/5n=4
1n=4
n=4