1, travel problem: distance = speed × time,
In the clock problem, a circle is 60 minutes, the minute hand speed is 1 min/min, and the hour hand speed is (112) min/min.
In the pursuit problem, the distance between them is = (speed A- speed B) × time.
2. Engineering problems: workload = working efficiency × working time
If the workload does not give a specific value, the unit is 1. Work efficiency is expressed by (1/ completion time).
3, concentration problem:
Solute = solution × concentration
Solution = solute+solvent
Constant Solute Relation Equation before and after Common Configuration
4. Number problem: For example, abc with three digits can be expressed as (100a+ 10b+c), and then the problem can be solved by an equation.
5, commodity profit problem:
Profit = selling price-buying price
Selling price = list price × discount = purchase price ×( 1+ profit rate)
Profit rate = profit/purchase price
6. Bank storage problems:
Interest rate = interest/principal
Interest = principal × annual interest rate× year
Sum of principal and interest = principal+interest = principal ×( 1+ annual interest rate× year)
7, navigation problems:
Downstream speed = ship speed+current speed
Countercurrent speed = ship speed-current speed
This topic is a typical engineering problem, please read it carefully.
1, if A works alone for 30 hours, then A's work efficiency is (1/30).
The cooperation between Party A and Party B is completed within 24 hours, so the sum of Party A's efficiency is (1/24). At this time, it can be calculated that Party B's work efficiency is (1/24)-(1/30) =1120, that is, Party B completes it alone.
Solution: Let the remaining B take X hours to complete, and there is an equation.
[( 1/24)-( 1/30)]* x = 1-[( 1/30)* 10]
The solution, x=80,
A: It takes 80 hours to complete, and it takes 1 hour to complete all (1120).
2. Set the rest of the cooperation, including
( 1/24)* x = 1-[( 1/30)* 10]
x= 16
A: Cooperation, 16 hours.
3. A first worked 10 hour and finished (1/30)* 10.
B did it for another five hours, and finished it (1120) * 5.
Assuming that the cooperation is completed within x hours, use (1/24) x.
There is also an equation for all work units that add up to 1.
( 1/30)* 10+( 1/ 120)* 5+( 1/24)x = 1
x= 15，
A: It takes 15 hours to complete!
Do you understand ~ ~:) Do more problems, master various types, and use their relationships to make equations, and there will be no problem. Come on, you can do it! ! !