1. The sum of two prime numbers is 20, and the difference is 6. What are the two prime numbers? 2. The sum of five consecutive odd numbers is 155. What are the five odd numbers? 3. When Jiajia turned on the light, she pulled the switch seven times in a row. Now is the light on or not? 100 times? 765 times?

(1) Let these two prime numbers be x and Y respectively
x+y=20 ①
x-y=6 ②
①+②：2x=26
∴x=13,y=7
That is, the two prime numbers are 7 and 13 respectively
(2) Let the number in the middle be x, then the other four are x-4, X-2, x + 2, x + 4
x-4+x-2+x+x+2+x+4=155
5x=155
∴x=31
The five odd numbers are 27, 29, 31, 33 and 35 respectively
(3) According to the meaning of the title: even number of times is off, odd number of times is on
The light is on at 7, not at 100 and on at 765

The sum of two prime numbers is 20 and the difference is 6. What are the two prime numbers

Using sum difference formula
（20+6）÷2=13
（20-6）÷2=7
So the prime numbers are 7 and 13

Two different prime numbers, their sum is 20, the difference is 6, they are () and ()

Two different prime numbers, their sum is 20, the difference is 6, they are (7) and (13)

How to calculate the three numbers 123 with the same result by adding and multiplying three natural numbers

1 x 2 x 3 = 1x2x3

One is equal to one part plus one part plus one part

1=1/2+1/3+1/6

2 out of 5 plus 3 out of 8 plus 1 out of 10 is equal to

12/20

7 out of 8 plus 5 out of 6 equals

Equal to 21 / 24 + 20 / 24 = 41 / 24, 41 / 24

What's 8 out of 9 plus 7 out of 6

37 out of 18

A fraction is equal to three fifths, and a fraction is equal to a few fifths

One fifths is equal to three fifths and two tenths. There is only one fifths in the number of 1-9, and the last one cannot be filled in

(1 / 6 + 1 / 8) * 24 * 2 / 9

14/9