Let \( b_2 \) be the number of bikes, \( c_2 \) be the number of cars, and \( t_2 \) be the number of trucks manufactured in 2022.
The problem provides the following relationships:
1. \( b_1 = 0.4 \times b_2 \) (2021 bikes vs. 2022 bikes)
2. \( t_2 = 1.25 \times t_1 \) (2022 trucks vs. 2021 trucks)
3. \( b_2 + c_2 + t_2 = 120,000 \) (Total vehicles in 2022)
4. \( t_2 = \frac{b_2 + c_2}{2} \) (Average of 2022 bikes and cars equals 2022 trucks)
5. \( c_1 = 0.9 \times c_2 \) (2021 cars vs. 2022 cars)
6. \( b_1 = \frac{1}{4} \times t_1 \) (2021 bikes vs. 2021 trucks)
Now, the solution proceeds step-by-step:
Step 1: Total vehicles in 2022.
The total number of vehicles in 2022 is 120,000:
\[b_2 + c_2 + t_2 = 120,000\]
Step 2: Bikes and trucks in 2021.
Using \( b_1 = \frac{1}{4} \times t_1 \) and substituting \( b_1 = 0.4 \times b_2 \):
\[0.4 \times b_2 = \frac{1}{4} \times t_1 \quad \Rightarrow \quad t_1 = 1.6 \times b_2\]
Step 3: Relationships between bikes, cars, and trucks in 2022.
From \( t_2 = \frac{b_2 + c_2}{2} \), substitute into the total vehicles equation:
\[b_2 + c_2 + \frac{b_2 + c_2}{2} = 120,000\]
Simplifying:
\[\frac{3}{2} \times (b_2 + c_2) = 120,000\]
\[b_2 + c_2 = 80,000\]
Substitute \( c_2 = 80,000 - b_2 \) into the equation for \( t_2 \):
\[t_2 = \frac{b_2 + (80,000 - b_2)}{2} = 40,000\]
Step 4: Solving for the number of cars.
Since \( t_2 = 40,000 \), and \( t_2 = 1.25 \times t_1 \):
\[40,000 = 1.25 \times t_1 \quad \Rightarrow \quad t_1 = 32,000\]
Using \( t_1 = 1.6 \times b_2 \):
\[32,000 = 1.6 \times b_2 \quad \Rightarrow \quad b_2 = 20,000\]
Finally, substitute \( b_2 = 20,000 \) into \( b_2 + c_2 = 80,000 \) to find \( c_2 \):
\[20,000 + c_2 = 80,000 \quad \Rightarrow \quad c_2 = 60,000\]
Step 5: Conclusion.
The number of cars produced in 2022 is \( \boxed{60,000} \).