90=21x+6

Solution for 90=21x+6 equation:

Simplifying
90 = 21x + 6

Reorder the terms:
90 = 6 + 21x

Solving
90 = 6 + 21x

Solving for variable 'x'.

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

Add '-21x' to each side of the equation.
90 + -21x = 6 + 21x + -21x

Combine like terms: 21x + -21x = 0
90 + -21x = 6 + 0
90 + -21x = 6

Add '-90' to each side of the equation.
90 + -90 + -21x = 6 + -90

Combine like terms: 90 + -90 = 0
0 + -21x = 6 + -90
-21x = 6 + -90

Combine like terms: 6 + -90 = -84
-21x = -84

Divide each side by '-21'.
x = 4

Simplifying
x = 4