42=21y

Solution for 42=21y equation:

Simplifying
42 = 21y

Solving
42 = 21y

Solving for variable 'y'.

Move all terms containing y to the left, all other terms to the right.

Add '-21y' to each side of the equation.
42 + -21y = 21y + -21y

Combine like terms: 21y + -21y = 0
42 + -21y = 0

Add '-42' to each side of the equation.
42 + -42 + -21y = 0 + -42

Combine like terms: 42 + -42 = 0
0 + -21y = 0 + -42
-21y = 0 + -42

Combine like terms: 0 + -42 = -42
-21y = -42

Divide each side by '-21'.
y = 2

Simplifying
y = 2