I need help with these questions
For 21)
A:y=x+4
B:y=2x
C:2x+2
D:2/3x+1

19.
Option (B) is the correct one.

Explanation:

The equation of line be is ,
y = 2x-4,

we have general equation give by,
y = mx +c

wherr m is the slope of the line and x and y are the coordinates changing,

Comparing these two we get the slop of line B as 2.

A thing you need to know here that product of slopes of a line perpendicular to another is -1.
Using this relation,

The slope of line a will be -1/2.

Let A pass through a coordinate (x,y).

Now,

Slope will be give by,


20.
Option (A) is the correct one.

How?:

Equation of line B is y = 3x-1.

Once again using the general equation for a line,
y =mx+c
Slope of B will be 3.

Now for a pair of parallel lines their slopes are equal.

So,
Slope of A must also be 3.

Applying the generation equation for a line on A gives,

y = 3x+c

Since A is passing though coordinates (2,4) the values must satisfy this equation,

So we have,


Now that we have value for c.
We can get the the equation we need.
So we have,

y = 3x -2.

Hope it helps.