please help will mark brainliest

Answer:
a, R=P+C
b,$870
Step-by-step explanation:
a if P=R‒C.(to find R you have to know the opposite of ‒C) ( -C≠C)
then add C in two sides
(P+C=R‒C+C)
(P+C=R)
SO the formula is R=P+C
b the given are P=$350,C=$520
R=$350+$520
R=$870
i believe it helps you