Substitute numbers for the letters to make the equation true. Same letter has the same number. Different letters have different numbers.
x + x + y = 20
y + a - y = 9
y + x = 13
omygod i know the answer now... i solved hahaha. nevermind
To solve this problem, we need to assign numerical values to the letters that satisfy the given equations. We can start by examining the first equation: x + x + y = 20.
Since the equation involves two occurrences of x, they must be assigned the same number. This tells us that x + x is equal to 2 times x. So, we can rewrite the equation as 2x + y = 20.
Now let's look at the second equation: y + a - y = 9.
Since y is added and subtracted within the equation, we can conclude that the y values cancel each other out, leaving us with a = 9.
Finally, let's analyze the third equation: y + x = 13.
Now that we know the value of a from the second equation, we can substitute it in this equation, giving us y + x = 13.
At this point, we've determined that a = 9. Now, we can solve for x and y by substituting the known values into the equations.
From the first equation, which is 2x + y = 20, we substitute y with a value of 9 (from the second equation), resulting in 2x + 9 = 20.
By subtracting 9 from both sides of the equation, we find that 2x = 11. Dividing both sides by 2, we get x = 5.5.
Lastly, we substitute the value of x (5.5) into the third equation, y + x = 13, giving us y + 5.5 = 13.
By subtracting 5.5 from both sides, we find that y = 7.5.
Therefore, the solution that satisfies all three equations is x = 5.5, y = 7.5, and a = 9.