Math Problem Statement

The system of equations describes the situation in the image. Solve for the price of a banana and a sandwich based on the given equations: 4x + y = 38 3x + 2y = 46

Solution

The problem involves solving the system of equations provided to find the prices of a banana and a sandwich. Let us denote:

  • xx: the price of a banana (in kr)
  • yy: the price of a sandwich (in kr)

The equations are:

4x+y=384x + y = 38 3x+2y=463x + 2y = 46

Step 1: Solve for yy in terms of xx from the first equation:

y=384xy = 38 - 4x

Step 2: Substitute y=384xy = 38 - 4x into the second equation:

3x+2(384x)=463x + 2(38 - 4x) = 46 Expand and simplify: 3x+768x=463x + 76 - 8x = 46 5x+76=46-5x + 76 = 46 5x=30-5x = -30 x=6x = 6

Step 3: Substitute x=6x = 6 into y=384xy = 38 - 4x:

y=384(6)y = 38 - 4(6) y=3824y = 38 - 24 y=14y = 14

Final Results:

  • The price of a banana (xx) is 6 kr.
  • The price of a sandwich (yy) is 14 kr.

Would you like more detailed steps or additional explanations? Let me know!


Here are 5 follow-up questions:

  1. How would the results change if the price of four bananas and a sandwich was increased to 50 kr?
  2. Can you write the problem as a matrix equation and solve it using matrix methods?
  3. How would you solve this system graphically?
  4. Can you verify the solution by substituting x=6x = 6 and y=14y = 14 back into both equations?
  5. What happens to the system if the coefficients of xx and yy in the second equation are doubled?

Tip: To verify your results, substitute the values back into the original equations to ensure they hold true.

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Math Problem Analysis

Mathematical Concepts

Algebra
Systems of Linear Equations

Formulas

Substitution method
Linear equations

Theorems

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Suitable Grade Level

Grades 8-10