(1.3-2.1a)(4.2)=3.36

Solution for (1.3-2.1a)(4.2)=3.36 equation:

Simplifying
(1.3 + -2.1a)(4.2) = 3.36

Reorder the terms for easier multiplication:
4.2(1.3 + -2.1a) = 3.36
(1.3 * 4.2 + -2.1a * 4.2) = 3.36
(5.46 + -8.82a) = 3.36

Solving
5.46 + -8.82a = 3.36

Solving for variable 'a'.

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

Add '-5.46' to each side of the equation.
5.46 + -5.46 + -8.82a = 3.36 + -5.46

Combine like terms: 5.46 + -5.46 = 0.00
0.00 + -8.82a = 3.36 + -5.46
-8.82a = 3.36 + -5.46

Combine like terms: 3.36 + -5.46 = -2.1
-8.82a = -2.1

Divide each side by '-8.82'.
a = 0.2380952381

Simplifying
a = 0.2380952381