Solve the following and express each answer in scientific notation and to the correct number of significant figures.
A). (5.3 x 10^4) + (1.3 x 10^4)
B). (7.2 x 10^-4) /(1.8 x 10^3
C). 10^4 x 10^-3 x 10^6
D). (9.12 x 10^-1) - (4.7 x10^-2
E). (5.4 x 10^4) x (3.5 x 10^9)