The mean, median, and mode of the 7 data values 60,100,x,40,50,200,90 are all equal to x. What is the value of ?

Let a, b and c be positive integers. The sum of 160 and the square of a is equal the sum of 5 and the square of b. The sum of 320 and the square of a is equal to the sum of 5 and the square of c, a is

all positive integers appear in the sequence 1,2,2,3,3,3,4,4,4,4,..,and each positive  integer k appears i the sequence k  time . in the sequence, each term after the first is greater than or equal of the term before it. if the intrger  12 first is appears in the sequence as the nth term ,what is the value of n ?

A)62       B)66       C) 65      D)67        E)64

Let a, b and c be positive integers. The sum of 160 and the square of a is equal the sum of 5 and
the square of b. The sum of 320 and the square of a is equal to the sum of 5 and the square of b.
Find a.

Câu 9:
Three different positive integers and are such that .
What is the value of ?
Answer:
Câu 10:
Of the numbers 1,2,…,1000, how many numbers are divisible by neither 6 nor 9?
Answer:

It is known that xx and yy are both positive integers and 6x−9y=36x−9y=3, find the minumum value of x.

The area of a rectangle is 80. The width and length are integers. Find the smallest value of the perimeter. 

Giúp mình nhé 

1.Find the greatest negative integer value for n so that:

n⁴ - 25n² - 70n - 49 

2.Toán tiếng anh: If the length of a leg of a right angle is 11 and the lengths of the other two side are both positive integers, then the perimeter of a triangle is.............

Help me please !!

Find the value of n, if the sum of even positive integers between n² - n + 1 and n² + n + 1 is a number between 2500 and 3000