2. A mountain road, from the foot of the mountain to the top of the mountain, takes 1 hour, but it is still 1 km. You can walk from the top of the mountain to the foot of the mountain in 50 minutes. It is known that the speed of downhill is 0.5 times that of 65438+ uphill. How many kilometers per hour are you going uphill and downhill? How many kilometers is this mountain road?

There is a barge with a deadweight of 800 tons and a volume of 795 cubic meters. Now, cotton and pig iron are transported. The volume of pig iron per ton is 0.3 cubic meters, and the volume of cotton per ton is 4 cubic meters. How many tons of pig iron and cotton can be loaded to make full use of the load and volume of the ship?

4、 1+(-3)+5+(-7)+9+(- 1 1)...+97+(-99)=

5、2a-b-c/a^2-ab-ac+bc

+2b-c-a/b^2-ab-bc+ac

+2c-a-b/c^2-ac-bc+ab.

6、 1+3+3^2+3^3+3^4+3^5+………………+3^2005=?

7. There are 6 taxis in a taxi stand. After the first taxi leaves, a taxi leaves every 4 minutes. Two minutes after the first taxi left, a taxi pulled into the station. After that, a taxi will return to the station every 6 minutes. After the original taxi leaves once, another taxi leaves every 4 minutes. Q: "After the first taxi leaves, how long will it take at least for the station to leave on time?" ?

8. Given X = Y = 1 of a-b and C-A, what is the value of x+y?

9、2000*5-2×2000*4- 1998)÷(2000*5+2000*4-200 1)

10、(2×5+2)(4×7+2)(6×9+2)……(2002×2005+2)÷( 1×4+2)(3×6+2)(5×8+2)……(200 1×2004+2)

I tried my best!