MAAYOS PO NA SAGOT. NON-SENSE = Report ASAP po (kahit wala na explanation basta tama po ang sagot, magcocomment na lang ako kung kailangan ko ng clarification. Advance tysm)

1) Jaden can build a deck by himself in 20 hours. His brother, Jarod can build the same deck in 30 hours. How long will it take them to build the deck if they work together?
a. 32
b. 25
c. 15
d. 12

2) Jacob travelled 20 miles upstream and returned to his camp in 7 hours. If the speed of the water's current was 3 miles per hour, what was the speed of Jacob's boat in still water?
a. 10
b. 4
c. 7
d. 3