They are all pretty easy all you do is multiply the cost by the amount of things you buy. For example number 4 your variables are cost (c) and songs (s). Your equation is c•s so $0.99 • s. 50 songs would be .99 • 50 which is $49.50
Since it is perpendicular to y=3x-1, the slope must be a negative reciprocal.
there the slope of the perpendicular line is

So now we have,

To find b, we use the point that the line passes through and substitute it to the y and x values.

which would give us b=5/3
Therefore, the equation of the line is
Answer: 8x+12
Distribute the 4. So, 4(2x)+4(3). Then you end up with 8x+12.
The answer is 7859
I did it and got it right.....