The average monthly salary of the workers in a workshop is ₹$8,500$. If the average monthly salary of $7\text{workers}$ is ₹$10,000$ and average monthly salary of the rest is ₹$7,800$, the total number of workers in the workshop is:

Let the total number of workers in the workshop be $N$.
The number of remaining workers is $N-7$.

According to the question, the total salary of all workers is the sum of the salaries of the $7$ workers and the remaining workers:

$$\text{Total Salary}=8500\times N$$

Also,

$$\text{Total Salary}=(7\times 10000)+(N-7)\times 7800$$

Equating both expressions:

$$8500N=70000+7800N-54600$$

$$8500N-7800N=15400$$

$$700N=15400$$

$$N=\frac{15400}{700}=22$$

Thus, the total number of workers in the workshop is $22$.