10(0.1d-0.3)=0.2(d+21)

Solution for 10(0.1d-0.3)=0.2(d+21) equation:

Simplifying
10(0.1d + -0.3) = 0.2(d + 21)

Reorder the terms:
10(-0.3 + 0.1d) = 0.2(d + 21)
(-0.3 * 10 + 0.1d * 10) = 0.2(d + 21)
(-3 + 1d) = 0.2(d + 21)

Reorder the terms:
-3 + 1d = 0.2(21 + d)
-3 + 1d = (21 * 0.2 + d * 0.2)
-3 + 1d = (4.2 + 0.2d)

Solving
-3 + 1d = 4.2 + 0.2d

Solving for variable 'd'.

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

Add '-0.2d' to each side of the equation.
-3 + 1d + -0.2d = 4.2 + 0.2d + -0.2d

Combine like terms: 1d + -0.2d = 0.8d
-3 + 0.8d = 4.2 + 0.2d + -0.2d

Combine like terms: 0.2d + -0.2d = 0.0
-3 + 0.8d = 4.2 + 0.0
-3 + 0.8d = 4.2

Add '3' to each side of the equation.
-3 + 3 + 0.8d = 4.2 + 3

Combine like terms: -3 + 3 = 0
0 + 0.8d = 4.2 + 3
0.8d = 4.2 + 3

Combine like terms: 4.2 + 3 = 7.2
0.8d = 7.2

Divide each side by '0.8'.
d = 9

Simplifying
d = 9