Yes, math can be challenging sometimes (mostly due to the horrible way its taught by teachers but I wont go on a rant about that today).
The Slope of a parallel line is obviously going to have the same slope as the line it is parallel to, which you already know.
But for perpendicular, how would we figure that out?
First, you need to understand whats going on. Picture a linear line. Now, look at the (0,0) point. To make it perpendicular, it must form 90 degrees with the other line. Now, to get the answer for a perpendicular line, you need to remember two steps.
1.) Change the sign to the opposite sign (negative would go positive and positive would go negative)
2.) You take the reciprocal of the line (That is what times that number would make that number equal one. 2 * 1/2 would be 1. You can also look at this by switching the denominator and numerator.
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Answer:

Explanation:
Combining the fractions, we have:
Answer:

Step-by-step explanation:
We can see the fractions
and
of cups.
It can be seen that denominator has 4 i.e. the fraction
.
Let us suppose, a unit is equal to
of a cup.
Susan was supposed to use
of a cup.
i.e. 5 units of butter was to be used.
But, actual recipe has only 3 units of butter.

a. 
Alternatively, we could have directly divided the given fractions:

Answer: x = -11
Step-By-Step:
We can start by combining like terms on the left side.
-20 - x = 4x - (3x - 2)
Now we need to distribute the negative on the right side.
-20 - x = 4x - 3x + 2
Now combine like terms on the right.
-20 - x = x + 2
Now add 20 to the other side
- x = x + 22
Subtract x from the left side.
-2x = 22
Now divide by -2.
x = -11
Problem 1: Plug in the given value into the function and evaluate.

Problem 2: Solve the equation for y.

add 7x to both sides to move it to the right side of the equation.

Divide both sides of the equation by 2 to get a single y variable on the left hand side.

Simplify the terms to get the the equation into slope-intercept form.
The slope of the line is 
I'm a unsure what Problem 3 is asking for sorry I hope the rest is helpful.