Well what two numbers multiply to get -8 and add to get -2?
Well, to get -8, we either have (-1,8),(-2,4),(-4,2),(-8,1)
8-1=7
-2+4=2
2-4=-2
1-8=-7
Thus it should be (-4,2),
This means we should get (X-4)(X+2)
Average of 10 people = 65
65 × 10 = 650
average of 5 people = 35
35 × 5 = 175
650 + 175 = 825
825 ÷ 15 = 55
the average reading time for the entire book club each day is 55 minutes a day
