Explain real numbers, rational numbers, and irrational numbers .

A rational number is a number that can be written as a ratio. That means it can be written as a fraction, in which both the numerator (the number on top) and the denominator (the number on the bottom) are whole numbers.

All numbers that are not rational are considered irrational. An irrational number can be written as a decimal, but not as a fraction.An irrational number has endless non-repeating digits to the right of the decimal point. Although irrational numbers are not often used in daily life, they do exist on the number line. In fact, between 0 and 1 on the number line, there are an infinite number of irrational numbers!

answer: 21$

step-by-step explanation:

$42 / $14 = 3   (ratio 3: 1)

$7 x 3 = $21