Answer:
18: 3/4
19: 5/8
20: 1/2
21: 9/10
22: 2/3
23: 5/6
24: 4/9
25: 2/7
26: 3/4
27: 7/10
28: 4/5 (I'm in a rush, so make sure to double check the answers)
Answer:
Part 1) The equation in slope intercept form is 
Step-by-step explanation:
Part 1) Write an equation in slope-intercept form for a line that passes through (3,4) (and has a y intercept of -8)
we know that
The equation of a line in slope intercept form is equal to

where
m is the slope
b is the y-intercept
we have


substitute

solve for m



therefore

First, you need to isolate w. So you get w = 2/3 divided by 4.
I made the 2/3 a decimal, as it is easier to work with: 0.6666 divided by 4 is 0.167.
0.167 is 1/6.
w = 1/6, or 0.167.
The best way to multiply complicated problems mentally* is to break them into chunks.
Start with 20 times 8 to get 160, and then 8 times 5 to get 40. Add these together to get 200. 200 times 3 is 600, and 20 times 200 is 4000. Add these together to get your final answer, 4600.
In other words 8 x 20 + 8 x 5 = 200 200 x 3 + 200 x 20 = 4600
*I assumed you meant mentally, because otherwise you'd just multiply longhand, multiplying two of the three numbers and then multiplying their product with the third.