Hi, this is the notation for inclusion of all real
numbers.

We can also state numbers which are positive or negative with a sign on top of the R notation like so:
Answer:
4
Step-by-step explanation:
Amount spent on coffee = 70 - 39.56 = 30.44
One pound costs 7.61, how many will cost 30.44
7.61 : 1 = 30.44 : X
7.61 = 30.44/X
X = 30.44/7.61
X = 4
Answer: the function as they change value from one interval to the next
Answer:
17-1/4y
Step-by-step explanation: