The weight of the Earth is 5.9736 x 10^24 Kg. The weight of Venus is 4.8685 x 10^24 Kg. What is the combined weight of the earth and venus?

10.8421 x 10^26 Kg
10.8421 x 10^23 Kg
10.8421 x 10^25 Kg
1.08421 x 10^25 Kg

Please also explain your answer so I know how to figure this out in the future, thanks!