How to calculate simple interest

• Simultaneous equations


  Pairs of equations that need to be solved by finding the pair of x and y values that have solutions for both
• Solving simultaneous equations using elimination


  1. Label equations 1 and 2

  2. Combine equations to eliminate x or y

  3. Solve for one variable

  4. Substitute to find other variable
• The basic idea with the elimination method is to combine the two equations to eliminate either the x's or the y's
• Simultaneous equations


  • 4x + y = 10

  3y = 2x - 19
• Steps to solve simultaneous equations by elimination

  1. Label equations 1 and 2

  2. Ensure both equations are in the form ax + by = c

  3. Get the same number of x's or y's in both equations

  4. Eliminate the x or y terms by subtracting the equations

  5. Solve for one variable

  6. Substitute to find the other variable
• Substituting the found values back into one of the original equations is a good way to double check the solution