A workshop to process a batch of parts, four days to complete two fifths of the total, if you do 54, just complete 50% of this batch of parts____________________ According to the conditions in the question, add a suitable question,

A workshop to process a batch of parts, four days to complete two fifths of the total, if you do 54, just complete 50% of this batch of parts____________________ According to the conditions in the question, add a suitable question,

How many parts are there in this batch
54 / (50% - 2 / 5) = 540

Three groups in a workshop work on a batch of parts, and the first group makes two seventh of the total
In a workshop, three groups work on a batch of parts. The first group makes two seventh of the total, the second group makes 1600 parts, and the third group makes half of the total of the first two groups. How many parts are there in total?
No equations!

First of all, "the parts made by the third group are half of the sum of the first two groups", so the sum of the two groups can be regarded as two, the third group as one, and the total number of parts is three, so the third group accounts for one third of the total number of parts;
Secondly, you should have learned the relation "the specific quantity corresponding to the scoring rate △ the scoring rate = the specific quantity corresponding to unit 1". Then unit 1 is the "total number of parts" in the problem, so you are required to get the scoring rate corresponding to the 1600 parts made by the second group, that is, 1-2 / 7-1 / 3 = 8 / 21;
Finally, we use 1600 △ 8 / 21 = 4200
It can be seen from the above that the comprehensive formula of this topic is: 1600 ÷ (1-2 / 7-1 / 3) = 4200
A: there are 4200 parts in this batch
I have tried my best to make the answer process complete and easy to understand. I hope my answer will help you_ ∩)o ~

When a workshop processes a batch of parts, the first day completes 8 / 9 of the second day, and the second day completes 3 / 7 of the total. It is known that the second day makes 100 more such parts than the first day, how many of these parts are there in total?

Eight out of nine of the next day was done on the first day, and three out of seven of the total on the second day
So (3 / 7) * (8 / 9) = 8 / 21,
The second day is 3 / 7-8 / 21 more than the first day = 1 / 21,
More than 100, accounting for 1 / 21 of the total,
So the total number is 100 (1 / 21) = 2100

A factory processes a batch of parts, and completes more than one-third of 24 parts in the first day, and less than one-third of 12 parts in the second day
On the third day, we finished the remaining 60 pieces

Let the total number of parts be X
1/3x+24+1/3x-12+60=x
1/3x = 72
x = 72x3
X = 216 pieces
A: the total number is 216