Question

4)-15 4/5-(-20 3/5)=5)-1 7/9-3 5/6=6)16/21-5 1/3=​

Answer 1

Ответ:

Сложение положительных и отрицательных дробей

Answer 2

Let's solve each of these arithmetic expressions step by step:

4. -15 4/5 - (-20 3/5):

First, we need to remember that subtracting a negative number is the same as adding a positive number. So, the expression becomes:

-15 4/5 + 20 3/5

Now, let's add the whole numbers separately:

-15 + 20 = 5

Next, we add the fractions. To add fractions, they need to have the same denominator. The denominators here are already the same (5), so we can add the numerators:

4/5 + 3/5 = 7/5

Now, let's add the whole number (5) and the fraction (7/5):

5 + 7/5

To add a whole number and a fraction, we first convert the whole number into a fraction with the same denominator as the fraction. In this case, the denominator is 5:

5 = 5/1

Now, we have:

5/1 + 7/5

To add fractions, we need a common denominator, which is 5 in this case. So, we multiply the first fraction's numerator and denominator by 5:

(5 * 5 + 7) / 5 = (25 + 7) / 5 = 32 / 5

Therefore, the result is:

-15 4/5 - (-20 3/5) = 5 2/5 or 5.4

5. -1 7/9 - 3 5/6:

To perform this subtraction, let's convert both mixed numbers into improper fractions:

-1 7/9 = -(9/9 + 7/9) = -16/9

3 5/6 = (3 * 6 + 5) / 6 = 23/6

Now, we have:

-1 7/9 - 3 5/6 = -16/9 - 23/6

To subtract fractions, we need a common denominator, which is 9 * 6 = 54 in this case. So, we convert both fractions to have the denominator of 54:

-16/9 = -(16/9 * 6/6) = -96/54

23/6 = (23/6 * 9/9) = 207/54

Now, the expression becomes:

-96/54 - 207/54 = -303/54

We can simplify this fraction by dividing the numerator and denominator by their greatest common divisor, which is 3:

-303/54 = -101/18

Therefore, the result is:

-1 7/9 - 3 5/6 = -101/18 or -5 11/18 or -5.56 (rounded to two decimal places)

6. 16/21 - 5 1/3:

To subtract a whole number from a fraction, we first convert the whole number into a fraction with the same denominator as the fraction. The denominator here is 21:

5 = 5/1

Now, we have:

16/21 - 5 1/3 = 16/21 - (5 * 3 + 1) / 3 = 16/21 - 16/3

To subtract fractions, we need a common denominator, which is 21 * 3 = 63 in this case. So, we convert both fractions to have the denominator of 63:

16/21 = (16/21 * 3/3) = 48/63

16/3 = (16/3 * 21/21) = 336/63

Now, the expression becomes:

48/63 - 336/63 = (48 - 336) / 63 = -288/63

We can simplify this fraction by dividing the numerator and denominator by their greatest common divisor, which is 9:

-288/63 = -32/7

Therefore, the result is:

16/21 - 5 1/3 = -32/7 or -4 4/7 or -4.57 (rounded to two decimal places)