The rationals being closed under subtraction means that if we start with two rational numbers and subtract them, we get another rational number. Choice c subtracts two rational numbers but gets the wrong answer, so isn't support for anything. Choice b is rational too because the square root of 4 is 2.
Answer: b
170 cm. The unknown length on the left is 21 cm
The surface area of a sphere is given by

We deduce

So, in your case, the radius is

The volume of a sphere is given by

So, we have

Answer:
24
Step-by-step explanation:
60% of 50 is equivalent to 24 so he answered 24 questions correctly
Answer:
1. 5 cups of yellow paint.
2. 15 cups of yellow paint to 3 cups of blue paint.
3. 1:5 is the proportional relationship.
4. 5 is the constant of proportionality, it represents the . of yellow cups of paint.
Step-by-step explanation:
sorry if 4 is wrong