Question

2 18/31 × a - 2,75 при a = 12,4

Answer 1

2 18/31 * a - 2.75 = 2 18/31 * 12.4 - 2.75 = 80/31 * 62/5 - 2.75 = 16 * 2 - 2.75 = 32 - 2.75 = 29.25

Answer 2

To evaluate the expression 2 18/31 × a - 2.75 when a = 12.4, we can follow these steps:

Step 1: Convert the mixed number 2 18/31 to an improper fraction. To convert 2 18/31 to an improper fraction, we multiply the whole number (2) by the denominator (31) and add the numerator (18) to get the new numerator. The denominator remains the same. 2 × 31 + 18 = 62 + 18 = 80 So, 2 18/31 is equivalent to the improper fraction 80/31.

Step 2: Substitute the value of a into the expression. Substituting a = 12.4, we have: 2 18/31 × 12.4 - 2.75

Step 3: Perform the calculations. Multiplying the fraction 80/31 by 12.4: (80/31) × 12.4 = (80 × 12.4) / 31 = 992 / 31

Now subtracting 2.75: 992 / 31 - 2.75

To perform the subtraction, we need to find a common denominator between 31 and 100 (the denominator of 2.75). The common denominator is 31 × 100 = 3100.

Converting 2.75 to the fraction with a denominator of 3100: 2.75 = 2.75 × (100/100) = 275/100

Now, let's subtract the fractions: 992 / 31 - 275 / 100

To subtract these fractions, we need to find a common denominator, which is already 3100.

Subtracting the fractions: (992 - 275) / 3100 = 717 / 3100

Therefore, 2 18/31 × a - 2.75, when a = 12.4, is equal to 717/3100.