Use the proper number of significant figures to express each value.
(a) [tex]$97.3+1.00-56.0=$
(b) [tex]$\left(2.8 \times 10^5\right)\left(9.99 \times 10^3\right)=$\times 10^9[/tex]
(c) [tex]$\frac{52.0 \times 10^4}{3.75 \times 10^{-2}}+4.37 \times 10^2=$