You've been doing that all this time and didn't even realize it !
Every plain old number that you ever see is a rational number.
Every equation that has plain old numbers next to the variables
is an equation with rational coefficients.
If a variable ever has (pi) or a square root or a trig function next to it,
then that's an irrational coefficient. But I'll just bet you haven't ever
seen any of these yet.
While you cannot solve 946x+642y=911 for numerical values of x and y, you can indeed solve 946x+642y=911 first for x and then for y:
-911 - 642y
For x: 946x+642y=911 becomes 946x = 911 - 642y, or x = ------------------
946
911-946x
For y: 946x+642y=911 becomes 642y = 911-946x, or y = ---------------
642
Answer:
A. is the appropriate answer to carl's proof
The swimmers unit rate is 4/3 laps per minute
I think the answer is c I hope I am correct