A subset of a set , by definition, is any set that contains no elements not in .  Each of the following subsets can be seen to have at least one such element, which is underlined here:

The remaining set can be seen to have only elements from :

This is the correct choice.

 is the union of sets  and  - the set of all elements that appear in either  or . These elements are:

which is a set with twelve elements.

For negative numbers, the bigger the value next to the negative sign, the smaller the number. For example,  is smaller than . 

Use the tenths digit (the one to the right of the decimal point) to order the numbers:

The negative numbers with a  in the tenths place are smaller than the numbers with a  in the tenths place.

Then, use the hundredths place to order the numbers:

 is smaller than  since  is larger than . 

 is smaller than  since  is larger than . 

A prime number has exactly two factors: 1 and itself. 85 is immediately disqualified: any number that ends in 5 has 5 as a factor.

First, use the tenths digit (the one to the right of the decimal point) to order the numbers.

The numbers with a 6 in the tenths place are smaller than the numbers with a 7 in the tenths place.

Then, use the hundredths place to order the numbers.

0.66 is smaller than 0.69 since 6 is smaller than 9.

0.70 is smaller than 0.71 since 0 is smaller than 1. 

When ordering objects from largest to smallest, you need to compare the numbers. The largest number will always be the largest object. In this case, the number  is bigger than  and  so the table comes first. The number  is bigger than  so the flower comes next. The number  is the smallest number, so the vase is the smallest object. 

When ordering objects from largest to smallest, you need to compare the numbers. The largest number will always be the largest object. In this case, the number  is bigger than  and  so the sun comes first. The number  is bigger than , so the moon comes next. The number  is the smallest number, so the star is the smallest object. 

When ordering objects from smallest to largest, you need to compare the numbers. The smallest number will be the smallest object. In this case, the number  is smaller than  and  so the moon is the smallest object. The number  is smaller than , so the sun is the next object. The number  is the biggest number, so the cloud is the largest object. 

When ordering objects from smallest to largest, you need to compare the numbers. The smallest number will be the smallest object. In this case, the number  is smaller than  and  so the cat is the smallest object. The number  is smaller than , so the dog is the next object. The number  is the biggest number, so the snake is the largest object.