Perform the following calculations and report your answer in scientific notation.
a. (3.4 x 102) + (9.3 x 103) =
b. (8.2 x 10-2) - (2.4 x 10-3) =
c. (1.8 x 104) x (3.7 x 105) =
d. (6.7 x 108) / (4.5 x 107) =