21z-42=3(8z-15)

Solution for 21z-42=3(8z-15) equation:

Simplifying
21z + -42 = 3(8z + -15)

Reorder the terms:
-42 + 21z = 3(8z + -15)

Reorder the terms:
-42 + 21z = 3(-15 + 8z)
-42 + 21z = (-15 * 3 + 8z * 3)
-42 + 21z = (-45 + 24z)

Solving
-42 + 21z = -45 + 24z

Solving for variable 'z'.

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

Add '-24z' to each side of the equation.
-42 + 21z + -24z = -45 + 24z + -24z

Combine like terms: 21z + -24z = -3z
-42 + -3z = -45 + 24z + -24z

Combine like terms: 24z + -24z = 0
-42 + -3z = -45 + 0
-42 + -3z = -45

Add '42' to each side of the equation.
-42 + 42 + -3z = -45 + 42

Combine like terms: -42 + 42 = 0
0 + -3z = -45 + 42
-3z = -45 + 42

Combine like terms: -45 + 42 = -3
-3z = -3

Divide each side by '-3'.
z = 1

Simplifying
z = 1