(252-0.8*80- 16)/0.8=2 15

2)B train speed 104km.

(54*3. 1*2- 12.4)/3. 1= 104

3) That is, two cars can meet at 2: 24 pm;

Suppose we can meet in t hours; that is

40*2+40*t+60t=500

T=4.4 hours, 4 hours and 24 minutes,

4) A =50 B = 12

A-B = 3...2

A+B =62

5) The price of a diary is 2.9 yuan.

5 diaries = buy 1 story book +5.8 yuan.

The price of a story book = the price of a diary *3 times.

Other issues

1) Bus B travels 88 kilometers per hour.

(50*3*2-30-6)/3=88

2) 2) The length of CF is 6 cm.

DE=EC*2

DE+EC= 12

DE=8 EC=4

EC/AB=CF/CF+BC

4/ 12=CF/CF+ 12

CF=6