Subtract 2 from both sides
-2u = -7u + 17 - 2
Simplify -7u + 17 - 2 to -7u + 15
-2u = -7u + 15
Add 7u to both sides
-2u + 7u = 15
Simplify -2u + 7u to 5u
5u = 15
Divide both sides by 5
u = 15/5
Simplify 15/5 to 3
u = 3