Answer:
The answer is d
Step-by-step explanation:
Answer:

Step-by-step explanation:
Collect like terms and calculate the sum
Answer:
300 seconds
Step-by-step explanation:
First, you have to know how much half a minute is. Half a minute is 30 seconds.
Second, you multiply 30 by 10 because he answered 10 questions.
30 * 10 = 300
So your answer is 300 seconds
Lastly, have a great day! :)
Answer:
D
Step-by-step explanation:
Because 90/5=18
Answer:
The correct options are 1, 3 and 4.
Step-by-step explanation:
We need to find the expressions whose simplified form is a rational number.
Rational number: If a number is defined in the form of p/q where p and q are integers and q≠0, then it is called a rational number.
For example: 0,2, 4.3 etc.
Irrational number: If a number can not defined in the form of p/q, where p and q are integers and q≠0, then it is called an irrational number.
First expression is

12 is a rational number.
Second expression is

is an irrational number.
Third expression is

21 is a rational number.
Fourth expression is

5 is a rational number.
Therefore, the correct options are 1, 3 and 4.