2k+3(2k-1)=21

Solution for 2k+3(2k-1)=21 equation:

Simplifying
2k + 3(2k + -1) = 21

Reorder the terms:
2k + 3(-1 + 2k) = 21
2k + (-1 * 3 + 2k * 3) = 21
2k + (-3 + 6k) = 21

Reorder the terms:
-3 + 2k + 6k = 21

Combine like terms: 2k + 6k = 8k
-3 + 8k = 21

Solving
-3 + 8k = 21

Solving for variable 'k'.

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

Add '3' to each side of the equation.
-3 + 3 + 8k = 21 + 3

Combine like terms: -3 + 3 = 0
0 + 8k = 21 + 3
8k = 21 + 3

Combine like terms: 21 + 3 = 24
8k = 24

Divide each side by '8'.
k = 3

Simplifying
k = 3