1. **Problem Statement:** We have three types of cars: Alto, Suzuki, and City. Their rental rates per day are unknown and denoted as $A$, $S$, and $C$ respectively.
2. **Given Information:**
- Three Alto, two Suzuki, and four City cars cost 106 per day: $$3A + 2S + 4C = 106$$
- Two Alto, four Suzuki, and three City cars cost 107 per day: $$2A + 4S + 3C = 107$$
- Four Alto, three Suzuki, and two City cars cost 102 per day: $$4A + 3S + 2C = 102$$
3. **Goal:** Find the values of $A$, $S$, and $C$.
4. **Method:** Solve the system of linear equations using substitution or elimination.
5. **Step 1: Write the system:**
$$\begin{cases} 3A + 2S + 4C = 106 \\ 2A + 4S + 3C = 107 \\ 4A + 3S + 2C = 102 \end{cases}$$
6. **Step 2: Eliminate one variable.** Multiply equations to align coefficients and subtract.
Multiply equation 1 by 2 and equation 3 by 4 to eliminate $C$:
$$6A + 4S + 8C = 212$$
$$16A + 12S + 8C = 408$$
Subtract first from second:
$$16A + 12S + 8C - (6A + 4S + 8C) = 408 - 212$$
$$10A + 8S = 196$$
Simplify by dividing by 2:
$$5A + 4S = 98 \, \,(1)$$
7. **Step 3: Eliminate $C$ using equations 2 and 3.**
Multiply equation 2 by 2 and equation 3 by 3:
$$4A + 8S + 6C = 214$$
$$12A + 9S + 6C = 306$$
Subtract first from second:
$$12A + 9S + 6C - (4A + 8S + 6C) = 306 - 214$$
$$8A + S = 92 \, \,(2)$$
8. **Step 4: Solve the system of two equations (1) and (2):**
$$\begin{cases} 5A + 4S = 98 \\ 8A + S = 92 \end{cases}$$
From (2), express $S$:
$$S = 92 - 8A$$
Substitute into (1):
$$5A + 4(92 - 8A) = 98$$
$$5A + 368 - 32A = 98$$
$$-27A = 98 - 368$$
$$-27A = -270$$
$$A = \frac{-270}{-27} = 10$$
9. **Step 5: Find $S$ using $A=10$:**
$$S = 92 - 8(10) = 92 - 80 = 12$$
10. **Step 6: Find $C$ using $A=10$, $S=12$ in one original equation, e.g., equation 1:**
$$3(10) + 2(12) + 4C = 106$$
$$30 + 24 + 4C = 106$$
$$54 + 4C = 106$$
$$4C = 106 - 54 = 52$$
$$C = \frac{52}{4} = 13$$
11. **Final Answer:**
- Rental rate for Alto ($A$) = 10 per day
- Rental rate for Suzuki ($S$) = 12 per day
- Rental rate for City ($C$) = 13 per day
Car Rental Rates
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