2.5x+3x = 22 X=4。

2. Solution: Let the upper level have x passengers and the lower level have 2X passengers. Equation.

X+2x = 5 1 gives X= 17.

3. solution: let b drive x kilometers per hour.

3 × 45+3x+ 17 = 272 gives x = 40.

4. Solution: Let the rectangle of the besieged city be x cm wide and 2X cm long.

The solution of (x+2x) × 2 = 72 gives x = 12.

5. Solution: X grams of oxygen can be produced per square meter of grassland every day. equation

For 5x = 76, X = 15.2.

6. Solution: 7x+1.2×10 =14.8, and the solution is x = 0.4.

7. solution: let the waist x cm. Equation.

38+2x = 98 gives x = 30.

8. Solution: Let the number of girls be x and the number of boys be1.2x. Let's do the equation.

X+1.2x =110 gives x = 50.

9. (This topic is incomplete)

10. solution: let car b drive at the speed of x kilometers per hour. Set the equation.

(30+x) × 3 = 176，x = 86/3。