Answer:
p=7Q/2
Explanation:
Original number of students:
p students to do 1 job in 25 days.
Let r= the rate for 1 student.
pr*25=1
pr*25=1 is the work rate equation for p students.
Lesser number of students:
p-Q students came to do the job and time required was 35 days.
(P-Q)*r*35=1.
The unknowns are p, Q and r
Equate the original number of students and the lesser number of students
pr*25=(P-Q)*r*35
25rp=35rp - 35Qr
Collect like terms
25rp-35rp = -35Qr
Divide both sides by -5
-5rp+7rp=- 7rp
It can be re written as
7rp-5rp=-7Qr
2rp=7Qr
Make p the subject of the formula
p=7Qr/2r
p=7Q/2
p=7Q/2 is the original number of students
-10rp = -35Qr
The system of these two equations can be solved for p. See the THREE unknown
variables, p, r, and Q. You might assume that either r or Q would be a constant.