2. Calculate and express the following in the correct units with the correct number of
significant figures
(a) 7.310 km + 5.70 km
(b)(3.26 x 10^-3mg)-(7.88 x 10^-5 mg)
(c) (4.02 x 10^6dm) + (7.74 x 10^7dm)
(d) (7.8 m - 0.34 m) + (1.15 s +0.82 s)