Answer:
R = 6
Step-by-step explanation:
Given the equation of the line is 2x - Ry = 30
We know that the equation of a line with a as x-intercept and b as y-intercept is 
Now convert the above given line to the standard form
Divide the line by 30 we get


Here the y-intercept is 30/R
Given y-intercept = 5

R = 6
Answer:

Step-by-step explanation:
The equation of the line that is parallel to the line we are trying to find is

We can recall that when two lines are parallel it means that they have the same slope. Therefore the slope of the line we are trying to find is also -4. We now know that:

Therefore the equation of the line is:


Answer:
The step 4 is not what he should have done. But the wrong is step 5, because if he added -2x both sides, it would give the following equation:

and not 
Note that in step 4 he should have added 2x and not -2x to both sides, but we still have the equality. The problem is that step 5 is totally wrong.
I don't know what answer is expected to this question, but I would mark step 5, because this is mathematically wrong.
Solving the equation

Using distribution

Add
both sides


Add 12 both sides

Divide both sides by 5

Lowest common denominator for 3,4,6 is 12
5/6 = 10/12
1/4 = 3/12
2/3 = 8/12
a)
10/12 + 3/12 = 13/12 = 1 1/12
So you need to use first and second cables
b)
3/12 + 8/12 = 11/12
To reach 1 yard Carl need 1/12 yard cable