Question

Solve x + 3y = 7 if x and y must be whole numbers.

{(0, 5), (1, 3), (2, 1)}

{(2, 1), (1, 4), (0, 7)}

{(1, 2), (4, 1), (7, 0)}

{(0, 5), (1, 4), (2, 1)}

Answer 1

You can plug in the values in and see which of them is correct. A coordinate is (x,y), so you can put the coordinates into the equation and see which set is correct. If you start with the first one:
We'll put in (0,5):
0+3(5)=7
15=7 is not true so A can't be the answer.
Next we'll go to B and use (2,1):
2+3(1)=7
5=7 is not true so B can't be the answer.
Now we'll go to C and use (1,2):
1+3(2)=7
7=7 this is correct so we'll use the second pair of coordinates in C, (4,1):
4+3(1)=7
7=7 This is correct so we'll now use the last pair in the set (7,0):
7+3(0)=7
7=7 Since all three of the coordinate pairs worked in C, C would be your answer :)

Answer 2

Thanks :)