also do not understand how to do this. I am not asking for answes, just examples.

Solve using the substitution method.

3x – 4y = 5

2x – y = 1

look at that second equation. You can easily solve it for y

namely
y = 2x-1
so use (2x-1) for y in the first equation

3 x - 4(2x-1) = 5
3 x - 8 x + 4 = 5
-5 x = 1
x = -1/5
then y = -2/5 -1 = -7/5

check that
-3/5 +28/5 = 25/5 = 5 yes, checks
-2/5 + 7/5 = 5/5 = 1, yes, so we have it