0.3(b+7)+0.7b=5.1

Solution for 0.3(b+7)+0.7b=5.1 equation:

Simplifying
0.3(b + 7) + 0.7b = 5.1

Reorder the terms:
0.3(7 + b) + 0.7b = 5.1
(7 * 0.3 + b * 0.3) + 0.7b = 5.1
(2.1 + 0.3b) + 0.7b = 5.1

Combine like terms: 0.3b + 0.7b = 1b
2.1 + 1b = 5.1

Solving
2.1 + 1b = 5.1

Solving for variable 'b'.

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

Add '-2.1' to each side of the equation.
2.1 + -2.1 + 1b = 5.1 + -2.1

Combine like terms: 2.1 + -2.1 = 0.0
0.0 + 1b = 5.1 + -2.1
1b = 5.1 + -2.1

Combine like terms: 5.1 + -2.1 = 3
1b = 3

Divide each side by '1'.
b = 3

Simplifying
b = 3