A Historian because they are describing what they see years later
X+y<=20 is false, because it tries to correlate the amount of hats and scarfs with the time, without considering the time to knit each object
x<=5 is correct, he can at most make 5 hats for more he is missing yarn
y<=8 is correct, same reasoning but with scarfs
5x+8y<=20 is false, it compares the yarn requirements with the total time
12x+6y<=20 is correct, a corrected version of the first constraint which uses the worktime of each object essentially meaning "the time worked on all objects has to be less than the 20 hour time total"
so
x<=5
y<=8
12x+6y<=20
are correct
39/25 as a percent is 156%
Substitute the value of x into the function;
f(0.25)=1/3(-5(0.25))
f(0.25)=1/3(-5(1/4))
f(1/4)=1/3(-5/4)
f(1/4)=-5/12
Therefore, the function would be at -5/12 when x=1/4
Hope I helped :)
For Times Square magnets, we have that the price of each magnet is 2 dollars / magnet, there are 4 magnets / set, and Tom buys 12 sets. For Statue of Liberty magnets, the price is 3 dollars / magnet, there are 5 magnets / set, and Tom buys 12 sets
We can make a table of these values:
Magnets Price ($$/magnets) Set Size (magnets/set) Quantity (sets)
T.S. 2 4 12
S. of L. 3 5 12
Now, we can use the formula
Total Cost = Number of Magnets Bought * Price = (Quantity * Set Size) * Price
So we see that
Cost of T.S. magnets = Quantity * Set Size * Price
= 12 sets * 4 magnets * 2 dollars = $96
set magnet
Cost of S. of L. magnets = Quantity * Set Size * Price
= 12 sets * 5 magnets * 3 dollars = $180
set magnet
So the total amount spent was $96 + $180 = $276.