Answer:
u = 3w-4.5
Explanation:
w being the independent variable assumes that u will become the dependent variable. Therefore the equation needs to turn into u = aw + b
-2u + 6w = 9
*subtract 6w from both sides
-2u = 9-6w
*divide both sides by -2
u = -4.5+3w
*rearrange to make it look nicer
u = 3w-4.5
therefore: the w value doesn't care what the u value is making it independent but the u value will change from the w value making it dependent