If x and y are positive integers such that y is a multiple of 5 and 3x + 4y = 600, then x must be a ...
If x and y are positive integers such that y is a multiple of 5 and 3x + 4y = 600, then x must be a multiple of which of the following?
Answer/Solution
10.
Steps/Work
If y is a multiple of 5, then 4y is also a multiple of 5.
3x = 600 - 4y
600 - 4y is even and it is a multiple of 5.
Thus x must also be even and a multiple of 5.
Therefore x must be a multiple of 10.
The answer is E.
3x = 600 - 4y
600 - 4y is even and it is a multiple of 5.
Thus x must also be even and a multiple of 5.
Therefore x must be a multiple of 10.
The answer is E.