Why is the sum of three ones equal to 12?

Why is the sum of three ones equal to 12?

If the three circles overlap each other, fill in the numbers from 1 to 7 so that the sum of every four numbers equals 19

7 filling center, three circles overlap area
4. Fill in the overlap area of two circles for 5 and 6
1. 2, 3 fill in the outer circle

(five 1's, five 3's, five 5's, five 7's), any five numbers can only be added when they add up to 24
1,1,1,1,1,
3,3,3,3,3,
5,5,5,5,5,
7,7,7,7,7,
In the above 20 numbers, choose any five numbers, add up to 24

11+3+3+7=24
11+3+5+5=24

What are the two digit numbers of seven when the sum of one digit and ten digit numbers?

70
16,61
25,52
34,43

One third of x minus two seventh of five is fourteen

x/3-5*2/7=14
x/3-10/7=14
7x-30=294
7x=324
x=324/7

How much is three minus one third?

8/3

Two thirds plus x equals seven ninths

2/3+x=7/9
x=7/9-2/3
x=7/9-6/9
x=1/9

9.8.7.1 four numbers can be calculated with + - × △ and the final result is equal to 1

(9+7)÷8-1=1

x: 42 is 5:10 out of 7

Cross multiplication or step-by-step calculation, 5 / 7:10 = 1 / 14 x / 42 = 1 / 14 x = 3, understand

How to calculate x + (x + 16.7) + (x-2.5) = 184.3

X+(X+16.7)+(X-2.5)=184.3
3X=184.3+2.5-16.7
3X=170.1
X=56.7