Two math problems, tell me the formula and why The water content of 100 tons of grapes measured in Xinjiang is 99% of 100, and that of grapes transported to Nanjing is 98% of 100. How many tons are left after the grapes are transported to Nanjing? There are two bags of rice, and the weight of the second bag is 4 / 7 of the second bag. If 8 and 2 / 5 kg are taken out of the first bag and put into the second bag, the two bags are equal, How many kilos each of these two bags of rice weighs? Tell me the formula and why. You can give more points. Please give details. Thank you

Two math problems, tell me the formula and why The water content of 100 tons of grapes measured in Xinjiang is 99% of 100, and that of grapes transported to Nanjing is 98% of 100. How many tons are left after the grapes are transported to Nanjing? There are two bags of rice, and the weight of the second bag is 4 / 7 of the second bag. If 8 and 2 / 5 kg are taken out of the first bag and put into the second bag, the two bags are equal, How many kilos each of these two bags of rice weighs? Tell me the formula and why. You can give more points. Please give details. Thank you

In Xinjiang, there are 99% water and 1% meat in grapes, so the quality of "meat" is 100 times 1% = 1 ton;
In Nanjing, there is less water and "meat" has not changed. 1 ton of "meat" accounts for 2% of the total mass, so the total mass = 1 divided by 2% = 50 tons is the final answer
2 should be "the weight of the second bag is 4 / 7 of that of the first bag". From the second condition, we can know that the difference between the two bags is 8 / 5 times 2 = 16 / 5 4 kg. From the first condition, the difference between the two bags is 3 / 7 of that of the first bag, so the first bag = 16 / 5 4 divided by 3 / 7 = 39 / 5 1 kg, and then multiplied by 4 / 7, the first bag is 22.5 / 2 kg

(two) to calculate
① The road repair team plans to build 4.8 kilometers. Actually, it has built 3 / 4 kilometers more than the plan. How many kilometers has it actually built? ② 50 people need to form a rectangle with a length of 30 meters and a width of 20 meters. What is the average distance between two adjacent people? (to be correct)

① 4.8 + 3 / 4 = 4.8 + 0.75 = 5.55km
② (30 + 20) x2 △ 50 = 2m
That is to say, 50 people should form a rectangle 30 meters long and 20 meters wide
I hope I can help you

1. Dig a canal. Now 30% of the total length has been completed. It is 5.2km away from the midpoint. How long is the canal?
2. There are 432 workers in the machine tool factory, of which 80% are male workers. How many are male workers

5.2/(50%-30%)=26km
432*[80/(80+100)]=192