Question

Given the following formula, solve for a.

Answer 1

Answer:

A. a = 2s - b -c

Step-by-step explanation:

Rearrange the equation in a way that you have only a on one side. When solving equations you can add, subtract, multiply or divide by the same number/variable/expression on the both sides.

$s = \frac{a + b + c}{2}$

Multiply by 2 to get rid of the fraction.

$s \cdot 2 = \frac{a + b + c}{2} \cdot 2$

On the right side the 2 cancels out:

$s \cdot 2 = a + b + c$

On the right side next to a are still b and c. But we want a alone. Subtract b.

$s \cdot 2 - b = a + b + c - b$

b - b on right side gives 0.

$s \cdot 2 - b = a + c + 0$

The step above is usually skipped, because number + 0 = number.

$s \cdot 2 - b = a + c$

Next to a there is still c. Subtract c.

$s \cdot 2 - b - c = a + c - c$

c - c on the left is 0.

$s \cdot 2 - b - c = a$

So our answer is:

$s \cdot 2 - b - c = a$

It can be rewritten to (change sides):

$a = s \cdot 2 - b - c$

And s · 2 can be rewritten to 2s:

$a = 2s - b - c$