Answer
a = $\frac{P - b + c}{2}$
Work Step by Step
Isolate a on one side of the equation:
P = 2a + b - c
Subtract b and add c to both sides:
P - b + c = 2a
Divide both sides by 2:
$\frac{P - b + c}{2}$ = a
You can help us out by revising, improving and updating this answer.
Update this answerAfter you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.