6, a and B two cement heap, originally a pile of cement is B pile, if from the pile of 6 bags to a pile, a pile of cement is B pile, the original total. 6, a and B two cement heap, originally a pile of cement is the 5/7 of B pile, if the 6 piles of piles from the B pile to a pile, a pile of cement is the 4/5 of the pile.

6, a and B two cement heap, originally a pile of cement is B pile, if from the pile of 6 bags to a pile, a pile of cement is B pile, the original total. 6, a and B two cement heap, originally a pile of cement is the 5/7 of B pile, if the 6 piles of piles from the B pile to a pile, a pile of cement is the 4/5 of the pile.

Let B be x, then a is a 5 / 7X series. An equation is
5/7x+6=4/5X
X = 70-50, 120 in all
I was in grade 2 last year, right

For a project, Party A and Party B work together for 10 days, party a work alone for 18 days, and Party B work alone for several days~~~~

If Party B works alone for X days, then
1/x+ 1/18=1/10
x=22.5
Party B works alone in 22.5 days

A pile of coal is transported in 6 hours by car a and 9 hours by car B. now, 20 tons of coal are transported by two cars and two hours. How many tons of coal are there in this pile?

Suppose there are x tons in this ton of coal
Then a will transport 1 / 6x per hour
Similarly, B transports 1 / 9x per hour
（1/6+1/9)x*2=20
X=36

For a project, Party A and Party B cooperate for 10 hours, Party A works alone for 18 hours, and Party B works alone for 1 hour. What percentage of the project can be completed?
Tomorrow

1/10-1/18=2/45
Party B can finish 2 / 45 of the project in one hour alone