Choose the One Alternative That Best Completes the Statement or Answers

Multiple Choice

Choose the one alternative that best completes the statement or answers the question.
Solve.
- $P = s _ { 1 } + s _ { 2 } + s _ { 3 }$ for $s _ { 3 }$

A) $s _ { 3 } = P - s _ { 1 } - s _ { 2 }$
B) $s _ { 3 } = s _ { 1 } + s _ { 2 } - P$
C) $s _ { 3 } = s _ { 1 } + P - s _ { 2 }$
D) $s _ { 3 } = P + s _ { 1 } + s _ { 2 }$