Turn equation around:
7u-9-12u=26
Combine like terms:
-12u+7u=-5u
This turns equation into:
-5u-9=26
Add -9 to both sides:
-5u-9=26
+9=+9 - and + cancel out
-5u=35
Divide by -5 to get “u” by itself:
-5u=35
———— -5 And -5 cancel making
-5 =-5 “u” By itself
u= -7
Hope this helps!