There are two equations in the question, both of which are wrong. There is no single fraction which will make both equations correct.
1
30
Yes -20 is a whole number or an integer because it has no fractions or decimals with it.
There are an infinite number of equivalent fractions. The simplest form is 9/10.
12
20
1
There are infinitely many possible answers. If the missing number is the second in the sequence, it could be part of an arithmetic progression and so equal 10.4, or it could be in geometric progression and so would be 4, or harmonic progression which would give 1/0.65 = 1.54, approx. Furthermore, he missing number cold be the first or third in the sequence.
There an infinite number of fractions between them. 1/4 is one of them.
30
Yes -20 is a whole number or an integer because it has no fractions or decimals with it.
There are an infinite number of equivalent fractions. The simplest form is 9/10.
12
Don't know about the number but 'missing' is misspelled
To subtract fractions, you need to find a common denominator. The common denominator for 10 and 4 is 20. So, rewriting the fractions with a denominator of 20, we get 6/20 - 5/20 which equals 1/20.
There are a infinite number of fractions that can be equivalent to four fifths. 8/10, 12/15, 16/20, 20/25 etc.
An infinite number of fractions do. This is because you can multiply it by the number one without changing it's value, and any number other than zero divided by itself equals one. This means you can multiply it by 2/2, 3/3, 4/4 and so on, giving you the fractions 3/4, 6/8, 9/12, 12/16, 15/20, etc.