Let the number of workers = x
Average salary of all the workers x = Rs 850
Total salary of all the workers = Rs 850x
Average salary of seven technicians = Rs 1,000
Total salary = 7 × 1,000 = Rs 7,000
Average salary of ( x - 7) workers = Rs 780
Total salary = (x - 7) 780
According to the statement,
850x=7,000+(x−7)780850x=7,000+780x−5,460850x−780=7,000−5,46070x=1,540 x=22 workers