Question 653
It would probably be easier if one one question was posted at a time. Here goes my shot at answering all four of them.
 
Solve for y: 
x - y = -5    This means to try to get y by itself, so subtract an x from each side.
 
-y = -x - 5   Don't forget the negative sign is still in front of the y. Next divide everything by -1.
 
y = x + 5   Now that the equation has been solved for y, plug in three different numbers for x to find three solutions to the equation.
 
y = 0 + 5         
(0, 5)
 
y = 1 + 5         
(1, 6)
 
y = 2 + 5         
(2, 7)
 
Equation 2:
Solve for y:
-2x + y = 7        Try to get y by itself, so add 2x to both sides.
 
y = 2x + 7         Plug in three different numbers for x to find three solutions.
 
y = 2(0) + 7
y = 0 + 7         
(0, 7)
 
y = 2(1) + 7
y = 2 + 7         
(1, 9)
 
y = 2(2) + 7
y = 4 + 7         
(2, 11)
 
Equation 3:
Solve for y:
3x - 4y = 12      Try to get y by itself. First subtract 3x from both sides.
 
-4y = -3x + 12    Divide everything by -4.
 
{{{y = (3/4)x - 3}}}   Now plug in three different numbers for x to find three solutions.
 
{{{y = (3/4)(0) - 3}}}
y = 0 - 3        
(0, -3)
 
{{{y = (3/4)(4) - 3}}}
y = 3 - 3        
(4, 0)
 
{{{y = (3/4)(-4) - 3}}}
y = -3 - 3       
(-4, -6)
 
Equation 4:
Solve for y:
-5x + 3y = -15    Try to get y by itself. First add 5x to both sides.
 
3y = 5x - 15      Now divide everything by 3.
 
{{{y = (5/3)x - 5}}}   Now plug in three different numbers for x to find three solutions.
 
{{{y = (5/3)(0) - 5}}}
y = 0 - 5        
(0, -5)
 
{{{y = (5/3)(3) - 5}}}
y = 5 - 5        
(3, 0)
 
{{{y = (5/3)(-3) - 5}}}
y = -5 - 5       
(-3, -10)
 
There are all four answers.