3(0.2+1.6y)+6y=-21

Solution for 3(0.2+1.6y)+6y=-21 equation:

Simplifying
3(0.2 + 1.6y) + 6y = -21
(0.2 * 3 + 1.6y * 3) + 6y = -21
(0.6 + 4.8y) + 6y = -21

Combine like terms: 4.8y + 6y = 10.8y
0.6 + 10.8y = -21

Solving
0.6 + 10.8y = -21

Solving for variable 'y'.

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

Add '-0.6' to each side of the equation.
0.6 + -0.6 + 10.8y = -21 + -0.6

Combine like terms: 0.6 + -0.6 = 0.0
0.0 + 10.8y = -21 + -0.6
10.8y = -21 + -0.6

Combine like terms: -21 + -0.6 = -21.6
10.8y = -21.6

Divide each side by '10.8'.
y = -2

Simplifying
y = -2