(20-5-3)x+45=300

12x +45=300

12x =255

x=255/ 12

A: In the next few days, at least 255/ 12 pieces will be processed every day on average.

Quantity to be completed in the next few days+45 pieces processed three days before construction = 300 pieces in total.

Solution: Suppose a candidate must answer the X question correctly to make the score not lower than 130.

10x-4(20-x)>= 130

10x-80+4x & gt； = 130

14x & gt； = 130+80

14x & gt； =2 10

x & gt= 15

A: Candidates must answer 15 correctly or above to get a score of not less than 130.

X's correct answer score+incorrect answer score (20-X) > = 130.

Solution: Each type of work has X employees, and each type of work has (150-x) employees.

x & gt=2( 150-x)

X>= 300-2 times

x+2x & gt； =300

X & gt= 100

1200x 100+800x50

= 120000+40000

= 160000 (yuan)

A: Each recruit for Type B 100, and each recruit for Type A is 50. The monthly salary is at least 160000 yuan.

Count the number of people first, then the price.