What number added to four and five-tenths, is twelve? 4.5 8.5 7.5 16.5

The correct option is 3.

Step-by-step explanation:

The given numbers are

0.3, 0.029, 0.003, 0.01

If we compare two or more numbers then the extreme left are compared. The one having the greater extreme left digit will be greater.

Compare first two numbers.

0.3 > 0.029

Now compare third number with smaller value.

0.029 > 0.003

Now compare fourth number with smaller value.

0.01 > 0.003

The number 0.003 is smaller than  0.3, 0.029 and 0.01.

Since 0.003 is least value. Therefore the correct option is 3.