The given formula 
Solve for y means we have to make y alone
\\
Add -10 on both sides, we get

As there is multiplication sign between r and y so to solve for y, divide both side by r

What is the total cost or it is unsolvable?
Answer:
27°
Step-by-step explanation:
XWY and VWY are supplementary
∴ XWY + VWY = 180°
∴ XWY = 180° - VWY
XYW and ZYW are supplementary
∴ XYW + ZYW = 180°
∴ XYW = 180° - ZYW
ΔXWY is a right triangle at X
∴ XWY + XYW = 90°
∴ 180° - VWY + 180° - ZYW = 90°
∴ 180° - 6x + 180° - 4x = 90°
∴ 360° - 10x = 90°
∴ 10x = 270°
∴ x = 27°
X is 16 so turn everything into a equation