2、 13 + 2a
3、 1、5x 0.5x
4、a - 4
5、 17
6、m? 2 m-5a
7、a - b a - b + c
8. (5.3+4.7)+a 2.4a+2.4? 2
9、3x - 5 4x - 5
10、5x
Second, 1,? 2、? 3、? 4、?
Third, 1, A 2, C 3, C 4, B 5, C 6, a.
Four. x = 10 x = 30.6 x = 45 y = 2.5
Verb (abbreviation for verb) negligence
Sixth, ellipsis
7. 1. Solution: Suppose there are X trees in the fourth grade. 2x - 40 = 120
2. Solution: Suppose that the first artificial earth satellite launched by the United States weighs X kilograms.
2x + 0.38 = 173 x = 86.3 1
3. solution: it takes x days for mercury to go around the sun.
4x + 13 = 365 x = 88
4. Solution: Let the unit price of white chalk be X yuan.
120x + 48 = 144 x = 0.8
5. Solution: We assume that water is X yuan per ton.
420x - 380x = 60 x = 1.5
March: 1.5? 420 = 630 (yuan)
April: 1.5? 380 = 570 (yuan)
6. solution: let the speed of train b be x kilometers.
(2x - 8)? 4 = 480 x = 64
A: 64-8 = 56 (km/h)
Intelligent gas station
Four spellings. Is 42 cm the most paper-saving? wrapping paper