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.
Multiply by 2 to get rid of the fraction.
On the right side the 2 cancels out:
On the right side next to a are still b and c. But we want a alone. Subtract b.
b - b on right side gives 0.
The step above is usually skipped, because number + 0 = number.
Next to a there is still c. Subtract c.
c - c on the left is 0.
So our answer is:
It can be rewritten to (change sides):
And s · 2 can be rewritten to 2s: