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The seventh grade mathematics classroom exercise book (2)4.4 Solution formula
1.x= 10y+8, x= 12y-2, x=48, y=4, 48 students, * * * renting 4 cars.

(1) substitute T = 0C, v= 100, T = 10C, V = 103.5L into v = pt+q.100 = op+q1,/kloc.

3. let a be x, b be y. 0.5x+0.7=35 ①, x+0.4 = 40②.① times 2-②, and y=30. Substitute y=30 into ①, 0.5x= 14, x= 18.

4. There are 200 football players and 0/50 basketball players/kloc.

5. let the total income be x and the expenditure be y yuan. ( 1+20%)X-( 1- 10%)= 12000+ 1 1400①,x-y= 12000 ②。 ① Multiply by 10-② Multiply by 9 to get x=42000 and y=30000.