Question

9 2/21+6 5/21-7 13/21=

Answer 1

Как решаем:

Сначала переводим смешанное число в обыкновенную дробь.

Чтобы перевести смешанное число в обыкновенную дробь, нужно знаменатель этой дроби умножить на целое число и прибавить к нему числитель.

Решение:

$9\dfrac{2}{21}+6\dfrac{5}{21}-7\dfrac{13}{21}\ = \ \\ \\ \\\dfrac{9 \cdot 21+2}{21}+\dfrac{6\cdot21+5}{21}-\dfrac{7\cdot21+13}{21}\ = \\\\\\\dfrac{191}{21}+\dfrac{131}{21}-\dfrac{160}{21}\ = \ \\\\\\\dfrac{191+131-160}{21} \ = \ \dfrac{162}{21} \ = \ \bold{7 \dfrac{15}{21}}$

Ответ: 7 15/21

Answer 2

To solve the given expression, we need to add and subtract the mixed numbers.

9 2/21 + 6 5/21 - 7 13/21

Let's start by adding the whole numbers together: 9 + 6 - 7 = 8.

Next, we add the fractions together. The denominators are the same (21), so we can simply add the numerators:

2 + 5 = 7 for the first fraction.

Now, we subtract the third fraction from the result:

7 - 13 = -6.

Combining the whole number and the fraction, we have:

8 - 6/21.

However, it's important to simplify the fraction. Both 6 and 21 are divisible by 3, so we can divide both numerator and denominator by 3:

8 - 2/7.

So, the final result is 8 - 2/7.