Answer:
1. 
2. 
3. 
Step-by-step explanation:
Standard form of a line is  .
.
If a line passing through two points then the equation of line is
 
where, m is slope, i.e., .
.
1.
The line passes through the points (7,-3) and (4,-8). So, the equation of line is
 
 
 
 
 
 
 
Therefore, the required equation is  .
.
2.
We need to find the equation of the line, in standard form, that has a y-intercept of 2 and is parallel to  .
.
Slope of the line :  
Slope of parallel lines are equal. So, the slope of required line is -2 and it passes through the point (0,2).
Equation of line is
 
 
 
Therefore, the required equation is  .
.
3.
We need to find the equation of the line, in standard form, that has an x-intercept of 2 and is parallel to  .
.
From part 2, the slope of this line is -2. So, slope of required line is -2 and it passes through the point (2,0).
Equation of line is
 
 
 
Therefore, the required equation is  .
.