2、a = 3b = 65； a = 5b = 39； a = 15 b = 13； a = 65 b = 3； a= 15 b= 13
3. Each book is priced at X yuan.
48/x+4=48/(x-2)
The solution is x=8.
So the retail price of exercise books is 8 yuan per copy.
4, the topic should be 5 1, and 52 cannot be calculated, if the topic is 5 1.
These three consecutive odd numbers are:
5 1÷3= 17
17-2= 15
17+2= 19
So,
Their product =15×17×19 = 4845.
5, divisible by 2, the unit is 2, 4, 6, 8, 0; Divisible by 5, the unit is 5,0; Can be divisible by 3, and the numbers on each bit add up to be divisible by 3, so
The largest three digits are 990.
The minimum decimal number is 100000020.
Divisible by 2, with units of 2, 4, 6, 8 and 0; Divisible by 5, the unit is 5,0; So B=0.
Can be divisible by 3, and the numbers on each bit add up to be divisible by 3, and 6+2+0=8, so A= 1 or 4 or 7.