A. The average of B is 45, the average of a and C is 36, and the average of B and C is 60 (1) What is the average of a, B and C? (2) How much is a, B and C?

A. The average of B is 45, the average of a and C is 36, and the average of B and C is 60 (1) What is the average of a, B and C? (2) How much is a, B and C?

According to the first sentence, the average number of a and B is 45, we can get a + B = 90, and then look at the second sentence, the average number of a and C is 36, we can also get a + C = 72, the same reason, according to the third sentence, the average number of B and C is 60, we can get B + C = 120, now a + B + A + C + B + C = 90 + 72 + 120 = 282

There are 10 identical red, green, white, black and blue balls in the box. How many balls can be found at least at one time to ensure that at least three balls have the same color?

This is the sixth grade mathematics wide angle, just learned
The worst idea: touch two red ones, two green ones, two white ones, two black ones and two blue ones, then touch another one. No matter which color it is, there are three
Formula: 2 + 2 + 2 + 2 + 2 + 1 = 11

Solving mathematics problems in grade four of primary school can't be solved by equation
There are seven numbers in a row, and their average is 60. The average of the first four numbers is 56, and the average of the last four numbers is 65. What is the fourth number?

56*4+65*4=484
484-60*7=64
The fourth number is 64
Method: the first step: the sum of the first four numbers and the last four numbers is actually equal to these seven numbers + the fourth number. The second step is to subtract the sum of these seven numbers to leave the fourth number