Thank you for clarifying! Based on what you've written, it seems like you're asking me to solve the expression "21 = (1/3) x (5 - y)". To do this, we can start by simplifying the right-hand side of the equation:
(1/3) x (5 - y) = (5 - y) / 3
Now we can substitute this expression back into the original equation:
21 = (5 - y) / 3
To solve for y, we can start by multiplying both sides of the equation by 3:
63 = 5 - y
Next, we can subtract 5 from both sides of the equation:
58 = -y
Finally, we can divide both sides of the equation by -1 to solve for y:
y = -58
Therefore, the solution to the expression "21 = (1/3) x (5 - y)" is y = -58.