.40n+.70(60-n)=31.2

Solution for .40n+.70(60-n)=31.2 equation:

Simplifying
0.40n + 0.70(60 + -1n) = 31.2
0.40n + (60 * 0.70 + -1n * 0.70) = 31.2
0.40n + (42 + -0.7n) = 31.2

Reorder the terms:
42 + 0.40n + -0.7n = 31.2

Combine like terms: 0.40n + -0.7n = -0.3n
42 + -0.3n = 31.2

Solving
42 + -0.3n = 31.2

Solving for variable 'n'.

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

Add '-42' to each side of the equation.
42 + -42 + -0.3n = 31.2 + -42

Combine like terms: 42 + -42 = 0
0 + -0.3n = 31.2 + -42
-0.3n = 31.2 + -42

Combine like terms: 31.2 + -42 = -10.8
-0.3n = -10.8

Divide each side by '-0.3'.
n = 36

Simplifying
n = 36