SAT math average

[Nyla]

SAT math average statistics

Could you help with the following question:
"The average of x and y is 10 and the average of x,y and z is 15. Find the value of z."

Thanks in advance!!

[Jack]

SAT math average question

"The average of x and y is 10 and the average of x,y and z is 15. Find the value of z."

The arithmetic mean, also known as average, is the sum of all the values in a list of numerical values divided by the number of items in the list.

"The average of x and y is 10" : (1)

"the average of x,y and z is 15" : (2)

Subtracting (1) and (2) you have that

[Nyla]

Thanks Jack!!