Question

2 2/5(12 3/4 - х ) + 4,5=21 Х=?

Answer 1

Ответ:

5,875

Пошаговое объяснение:

2 2/5(12 3/4 - х) + 4,5 = 21

2,4(12,75 - х) + 4,5 = 21

2,4(12,75 - х) = 21 - 4,5

2,4(12,75 - х) = 16,5

12,75 - х = 16,5 : 2,4

12,75 - х = 6,875

х = 12,75 - 6,875

х = 5,875

Answer 2

To solve the equation $2\frac{2}{5}(12\frac{3}{4} - x) + 4.5 = 21$ for $x$, follow these steps:

Step 1: Simplify the expression within the parentheses.

$12\frac{3}{4}$ is the same as $12 + \frac{3}{4}$. So,

$12\frac{3}{4} - x = 12 + \frac{3}{4} - x$

Step 2: Multiply $2\frac{2}{5}$ by the simplified expression:

$2\frac{2}{5}(12 + \frac{3}{4} - x)$

Step 3: Distribute the $2\frac{2}{5}$ to each term inside the parentheses:

$2\frac{2}{5} \cdot 12 + 2\frac{2}{5} \cdot \frac{3}{4} - 2\frac{2}{5}x$

Step 4: Calculate the products:

$\frac{12}{5} \cdot 12 + \frac{12}{5} \cdot \frac{3}{4} - 2\frac{2}{5}x$

Now, simplify each term:

$\frac{144}{5} + \frac{36}{5} - 2\frac{2}{5}x$

Step 5: Combine the fractions:

$\frac{144}{5} + \frac{36}{5} = \frac{180}{5} = 36$

So, the equation becomes:

$36 - 2\frac{2}{5}x + 4.5 = 21$

Step 6: Subtract 4.5 from both sides of the equation:

$36 - 4.5 - 2\frac{2}{5}x = 21 - 4.5$

$31.5 - 2\frac{2}{5}x = 16.5$

Step 7: Now, isolate the term with $x$. First, subtract 31.5 from both sides of the equation:

$-2\frac{2}{5}x = 16.5 - 31.5$

$-2\frac{2}{5}x = -15$

Step 8: Divide both sides by $-2\frac{2}{5}$ to solve for $x$:

$-2\frac{2}{5}x = -15$

$x = \frac{-15}{-2\frac{2}{5}}$

To simplify further, convert the mixed number $-2\frac{2}{5}$ to an improper fraction:

$x = \frac{-15}{-\frac{12}{5}}$

Now, divide the fractions:

$x = \frac{-15}{-\frac{12}{5}} \cdot \frac{5}{5}$ (Multiplying by 5/5 to get a common denominator)

$x = \frac{-75}{-12}$

Now, simplify the fraction by canceling out common factors:

$x=\frac{75}{12}$