AlgebraVery hardCars in a mixed car park
Algebra practice question
A car park contains only cars and motorbikes. There are 30 vehicles with a total of 84 wheels. How many cars are in the car park?
Answer: 12
4c + 2m = 84 and c + m = 30. Doubling the second and subtracting: 2c = 24, so c = 12.
Common wrong answers
- If you answered 6
- 6 halves 12, a slip in the final division.
- If you answered 18
- 18 is the number of motorbikes.
- If you answered 21
- 21 divides 84 by 4, ignoring the motorbikes.
More Algebra questions
- Very hard
For what value of c does the system 3x − 2y = 8 and 9x + cy = 5 have no solution? - Very hard
In the system 5x + 4y = 32 and 3x − 2y = 6, what is the value of 8x + 2y? - Very hard
The solution set of the inequality |ax − b| ≤ 6, where a and b are constants and a > 0, is 3 ≤ x ≤ 9. What is … - Very hard
The function f is linear, and for every value of x, f(x + 2) − f(x) = 6. If f(5) = 4, what is the value of f(0… - Very hard
In the system of equations 2x + 3y = 12 and 5x − 2y = k, where k is a constant, the solution (x, y) satisfies … - Very hard
In the xy-plane, the system of equations kx + 6y = 12 and 2x + (k − 1)y = 6, where k is a constant, has infini…
Not affiliated with the College Board. SAT is a trademark of the College Board.