Which shows the expression below simplified?
(2.2 x 10^-1) + (2.3 x 10^-2)
hint: you must have the same power of 10 before you can add.
a) 2.43 x 10^-2
b) 4.5 x 10^-1
c) 4.5 x 10^-2
d) 2.43 x 10^-1