3(a-5)+4(a+5)=21

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Solution for 3(a-5)+4(a+5)=21 equation:


Simplifying
3(a + -5) + 4(a + 5) = 21

Reorder the terms:
3(-5 + a) + 4(a + 5) = 21
(-5 * 3 + a * 3) + 4(a + 5) = 21
(-15 + 3a) + 4(a + 5) = 21

Reorder the terms:
-15 + 3a + 4(5 + a) = 21
-15 + 3a + (5 * 4 + a * 4) = 21
-15 + 3a + (20 + 4a) = 21

Reorder the terms:
-15 + 20 + 3a + 4a = 21

Combine like terms: -15 + 20 = 5
5 + 3a + 4a = 21

Combine like terms: 3a + 4a = 7a
5 + 7a = 21

Solving
5 + 7a = 21

Solving for variable 'a'.

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

Add '-5' to each side of the equation.
5 + -5 + 7a = 21 + -5

Combine like terms: 5 + -5 = 0
0 + 7a = 21 + -5
7a = 21 + -5

Combine like terms: 21 + -5 = 16
7a = 16

Divide each side by '7'.
a = 2.285714286

Simplifying
a = 2.285714286

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