39-3=36
55+5=60 copies
36= 12*3
60= 12*5
Because there are three more pens and five fewer books, three good students are more than five.
Therefore, the maximum number of three good students is 12.
2.
3 liters =3000 cubic centimeters
Bottom area: 50*30= 1500 cm2.
Water height: 3000/ 1500 = 2cm.
10-2=8 cm
3.
Let the molecule be X.
2(x+ 1)=3x- 1
The solution is x=3.
So the denominator is 8.
The score is 3/8.
4.252/36=7, 12x7=84, that is, the number b is 84.