Substitute Q=40, MR=MC= 140.

∫ tr-TC =1000 = p * 40-0.1* 403+6 * 402-140 * 40-3000, while P= 160, tr =

2) the demand curve is P=a-bQ, MR=a-2bQ, which is obtained by 1): Mr (40) = a-2b * 40 =140 ①160 = a-b * 40 ②.

Get a= 100 and b=0.5.

∴mr= 100-q,p= 100-0.5q

3)Ed=dQ/dP*(P/Q)=-2*4=-8

4)FC=3000，P=90，

AFC(40)=75, AVC = sac-AFC = 60 < 90, and the production can be continued.

P "Western Economics" has further deepened the research results of the Ministry of Education's "Reform Plan of Teaching Content and Curriculum System of Higher Education for 2 1 century", and is a revised version of the curriculum textbook for 2 1 century. "Western Economics" has been included in the "Eleventh Five-Year" national planning textbook project of general higher education. Western Economics accurately, concisely, popularly and comprehensively interprets the basic principles and methods of western economics, focuses on the latest achievements and major progress of western economics, and makes necessary comments on the theories and viewpoints of western economics, so as to guide students to correctly master and apply the principles and methods of western economics. Based on the second edition, Western Economics has enriched and updated its style, structure and content in view of the characteristics and requirements of western economics teaching in Chinese universities. Especially suitable for undergraduates and self-learners of economics and management. Western economics is equipped with teaching courseware suitable for teachers.

Writing process

Western Economics, edited by Chen Yinque, is responsible for the design and determination of the overall framework and writing outline of the book, the unified revision of the first draft in terms of text and content, and the compilation of most cases. The specific division of labor of each chapter is as follows: Chen Yinque (introduction, chapters 1 to 9), Liu Mingxian (chapters 10 and 12), Shi (chapter 8), (chapter 9) and Chen (chapter 11).

Introduction: Western economics comprehensively and systematically expounds the basic principles of economics from a horizontal perspective. From the logical structure, economics can be divided into two parts: microeconomic theory and macroeconomic theory. The first to seventh chapters are microeconomic theories, which mainly answer microeconomic questions such as what to produce, how much to produce, how to produce it and for whom, including equilibrium price theory, consumer behavior theory, producer behavior theory, market structure and pricing, factor market and income distribution, market failure and microeconomic policies. Chapter 8- 12 is macroeconomic theory, which mainly analyzes macroeconomic aggregate relationship, macroeconomic fluctuation and macroeconomic policy, including national income determination theory, economic growth and fluctuation, unemployment and inflation theory, macroeconomic equilibrium theory and macroeconomic policy theory under open conditions.