Answer:
16) 
17) y = -x - 4
18) y = -2x - 1
19) y = -2x
20)
Step-by-step explanation:
With the two points you find the slope using 
Then using that slope, plug the slope in with one of the points values of x and y into the point slope formula, and smiplify that into the y-intercept formula.
[ (12 - n)/7 ] = -1
12- n = -7
-n = -19
n = 19
If the first gardener can finish the job in 6 hours, it means that every hour he completes 1/6 of the job.
By the same logic, the second gardener completes 1/7 of the job per hour.
So, if they work together, they complete

of the job per hour.
So, after 42/13 of a hour, they'll complete the job. Since one hour is made of 60 minutes, 42/13 of a hour is

So, it will take them about 194 minutes to finish the job, i.e. about 3 hours and 14 minutes.
Answer:
450 people paid the discounted fare and 750 people paid the regular fare.
Step-by-step explanation:
let r be regular fares paid and d be discounted fares paid
Total fares = 0.8r + 0.4d = 780
Since 1200 people paid the fares,
r + d = 1200 = Total people
Rearrange this formula:
r = 1200 - d
Substitute r into Total Fares formula
Total fares = 0.8r + 0.4d
780 = 0.8(1200-d) + 0.4d
780 = 960 - 0.8d + 0.4d
780 = 960 - 0.4d
0.4d = 180
d = 450
Sub d=450 into Total people formula
r + d = 1200 = Total people
r + 450 = 1200
r = 1200-450
r = 750
450 people paid the discounted fare and 750 people paid the regular fare.
Answer:
56 cups of water
Step-by-step explanation:
Katrina drinks 0.5 gallons of water per day
We have 7 days in a week, hence, the number of gallons of water she drinks per week is calculated as:
1 day = 0.5 gallons
7 days = x
Cross Multiply
1 day × x = 7 days × 0.5 gallons
x = 7 days × 0.5 gallons/1 day
x = 3.5 gallons
Note that 16 cups = 1 gallon
The number of cups of water she drinks per week is
1 gallon = 16 cups
3.5 gallons = x
Cross Multiply
1 gallons × x = 3.5 gallons × 16 cups
x = 3.5 gallons × 16 cups/1 gallons
x = 56 cups
Therefore, Katrina drinks 56 cups of water in a week