Answer:
For the first 30 minutes, we will have a line with a given steepness, this will represent the 30 minutes riding at a fast pace.
Then he stops for 20 minutes, we will represent this with a constant line.
Then he again moves for another 30 minutes, but with a slower pace than in the first 30 minutes, then this line will be less steep than the first line.
A sketch of this situation can be seen below.
He buys three cups of hot choclate cause 1.50*3= 4.50
and he buys 5 cups of coffe cause 2.25*5=11.25
and 11.25 + 4.50=15.75
Answer: Yes
This graph passes the vertical line test. This is a test where we try to draw a single vertical line through more than one point on the curve. In this case, such a thing is not possible. Any input x leads to exactly one output y. This graph is a function.
The decimal representation of any number is a linear combination of powers of 10. In other words, given a number like 123.456, we can expand it as
for any 
, so the above is the same as
Similarly, we can write
Now it's a question of reducing the fraction as much as possible. We have 
so
It is11 because 5 plus 6 is 11
