Question 1189607
let x = the number right.
let y = the number wrong.


x + y = 24
5x - 3y = 0


these 2 equations need to be solved simultaneously.
the first equation tells you the total number right and wrong.
the second equation tells you the the scores for the number right and the scores for the number wrong.


multiply both sides of the first equation by 5 and leave the second equation as is to get:


5x + 5y = 120
5x - 3y = 0


subtract the second equation from the first to get 8y = 120


solve for y to get y = 120 / 8 = 15.


this makes x = 9 because 15 + 9 = 24.


5x - 3y becomes 5 * 9 - 3 * 15 which becomes 45 - 45 = 0.


that confirms the values of x and y are good.


the solution is that she got 9 correct and 15 wrong.


the two equations that needs to be solved simultaneously were:


x + y = 24
5x - 3y = 0