Question 831191
a.) Choose an {{{x}}} value then compute the {{{y}}} value.
I'll do one, you do the other two.
Let x=0,
{{{y=2x-5}}}
{{{y=2(0)-5}}}
{{{y=0-5}}}
{{{y=-5}}}
(0,-5)
.
.
.
.
b) Again using my first example, choose any {{{y}}} other than {{{y=-5}}} and {{{x=0}}}. 
(0,12) will fail the test
{{{12=2(0)-5}}}
{{{12=0-5}}}
{{{12=-5}}}
False, so (0,12) is not an ordered pair for that wequation.