Let x be the first of the four consecutive numbers.
Then x+1 is the second,
and x+2 is the third,
and x+3 is the fourth.
If their sum is 810, then
x + x+1 + x+2 + x+3 = 810
If you solve that equation for x, you'll have the answer to your question.
1.
Consider a group of n objects. Assume we want to form groups of r, from these n objects.
There are in total

many ways of doing so.
where, r! is "r factorial", calculated as 1*2*3*...*(r-1)*r
2.
C(x, 2) is the total number of pairs out of x objects, that we can form.
so let the x objects represent the x teams, and 2, represent a group of 2, which means a game.
The total number of games is:
n(x)=2*C(x, 2) =

Remark, we multiplied by 2, since there will be 2 matches for each pair of teams.
Answer:
Answer:
the correct answer is c
Step-by-step explanation:
Answer:
A, commutative
Step-by-step explanation:
Commutative property means that you can switch around the numbers, and get the same answer. However, the commutative property is only compatible for addition and multiplication. I.e. 2+6 equals 6+2, but 2-6 does not equal 6-2.