The sum of all the measurements is just the average times the number.


So if the average of all 92 is 7 the sum of those is

The average of the last two is 7.2 so their sum is

That means the sum of the first 90 is

so the average of the first 90 is

cm
Answer:
the answer is A -1/3 x
Step-by-step explanation:
hope this helps :)
The answer would be d , because you have to add how many of each fish to equal up to the sum of 420 . which is x y . so the first equation is x + y = 420 . then it says he bought 6 times as many parrotfish as he did angelfish so you would have to multiply x which represents angelfish by 6 . to get the second equation of y = 6x .
Pretty certain it would be the first answer - X = 6 square root of 2
Y = 6