Answer: (2x+3)(x+3)
Step-by-step explanation:
Looking at this, you know that it must look something like
(? +3)(?+3) , because they must multiply to 9. The ?s must multiply to 2x^2, the most plausible values being 2x and x, ending us up with (2x+3)(x+3)
4+2x = x (x = student in smaller group)
4 + 2x + x = 28 (total # of students)
4+ 3x = 28
3x = 24
x = 8
8 students in the smaller group
4 + 2(8) = 20 students in the larger group
I am assuming you want to solve for m in each case
8n = -3m + 1
8(-2) = -3m + 1
-16 = -3m + 1
-3m = -17
m = 
8(2) = -3m + 1
16 = -3m + 1
-3m = 15
m = -5
8(4) = -3m + 1
32 = -3m + 1
-3m = 31
m = 