A pile of coal has been transported 2:5. If 50 tons are being transported, the remaining coal will be 30 tons less than that already transported. How many tons of coal is the original pile of coal

A pile of coal has been transported 2:5. If 50 tons are being transported, the remaining coal will be 30 tons less than that already transported. How many tons of coal is the original pile of coal

The key to solve this kind of problem is to match the proportion with the actual value
At present, the proportion number is known, so we need to find out its corresponding value
If another 50t is transported, there will be 50t more transported and 50t less transported. At this time, there will be 30t more transported than not transported. Then, before the 50t is transported, there will be 50 + 50-30 = 70t less transported than not transported. That is to say, when x proportion has been transported, there will be 70t less transported than not transported
70 divided by the ratio difference is the total

Two tons of coal. The first pile weighs 25 tons. One fifth of the coal is transported from the first pile and put into the second pile. At this time, the first pile is 5 tons more than one sixth of the second pile. How many tons of coal is there in the second pile?

25 × (1-1 / 5) = 20 tons
20-5 = 15 tons
15 △ 1 / 6 = 90 tons
90-5 = 85 tons

There are two piles of coal. The first pile is 25.5 tons, and the second pile is 1.5 tons less than twice of the first pile. How many tons do these two piles of coal weigh?

25.5 + (25.5 × 2-1.5), = 25.5 + 49.5, = 75 tons; a: the total weight of these two piles of coal is 75 tons

There are two piles of coal. The original ratio of the first pile to the second pile is 12:7. One fourth of the coal is transported from the first pile. The second pile is 3.6 tons less than the first pile. How much is the first pile?

Now the ratio of the first pile to the second pile is 12 × (1 / 4): 7 = 9:7
Now the first pile has 3.6 △ (9-7) × 9 = 16.2 (tons)
In the first pile, 16.2 (1-1 / 4) = 21.6 (tons)