After translating this question, I understood it would form some kind of quadratic equation that can be a bit tricky to solve because numbers are not as small. So, I may have to use the answer choices.
Here is the equation I formed:
Time taken for 21 standard looms to complete the work is x, so for 6 industrial looms, this time becomes x-14
This gives us individual rates:
Rate of 1 standard loom= 1/21x ; Rate of 1 industrial loom = 1/6x-84
We fit this into the first equation given to us for 7 standard looms and 5 industrial looms:
7/21x + 5/6x-84 = 1/14- (1)
Now, we have to compute ratio of rates of 1 industrial loom to 1 standard loom: 21x/6x-84 - (2)
If we use options:
A: 3 - The ratio can not be 3, if we put this into x, we will get negative x and time taken can not be negative
B: 5- This gives an integer value of x, which could be true but still becomes complex
C- 6- Again integer value- eliminate for now
D- 7- This gives us a positive integer value of x, if we put into 1, the equation satisfies. I will go with this option
This is a shorter way to do it. We can solve the quadratic equation to get the value of x and then put it into (2) to find the ratio