3a+2(400-a)=1050

Solution for 3a+2(400-a)=1050 equation:

Simplifying
3a + 2(400 + -1a) = 1050
3a + (400 * 2 + -1a * 2) = 1050
3a + (800 + -2a) = 1050

Reorder the terms:
800 + 3a + -2a = 1050

Combine like terms: 3a + -2a = 1a
800 + 1a = 1050

Solving
800 + 1a = 1050

Solving for variable 'a'.

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

Add '-800' to each side of the equation.
800 + -800 + 1a = 1050 + -800

Combine like terms: 800 + -800 = 0
0 + 1a = 1050 + -800
1a = 1050 + -800

Combine like terms: 1050 + -800 = 250
1a = 250

Divide each side by '1'.
a = 250

Simplifying
a = 250