Solve: -1/2 + 3/4 - 1/5 - 4/5 Fraction Addition and Subtraction

Question

12+34+15+(45)= -\frac{1}{2}+\frac{3}{4}+-\frac{1}{5}+(-\frac{4}{5})=

Video Solution

Solution Steps

00:00 Solve
00:10 Positive times negative always equals negative
00:24 Multiply by 2 to find common denominator
00:35 Add the fractions
00:55 Write the whole fraction as a whole number
01:00 Calculate the numerator
01:04 Positive times negative always equals negative
01:11 Convert from whole number to whole fraction with common denominator
01:20 And this is the solution to the question

Step-by-Step Solution

To solve this problem, we must simplify the expression 12+34+(15)+(45) -\frac{1}{2} + \frac{3}{4} + (-\frac{1}{5}) + (-\frac{4}{5}) .

First, we need to find the least common denominator (LCD) for the fractions 2, 4, and 5. The LCD is 20.

Next, we convert each fraction to an equivalent fraction with the common denominator of 20:

  • 12-\frac{1}{2} becomes 1020-\frac{10}{20}
  • 34\frac{3}{4} becomes 1520\frac{15}{20}
  • 15-\frac{1}{5} becomes 420-\frac{4}{20}
  • 45-\frac{4}{5} becomes 1620-\frac{16}{20}

Now we perform the addition and subtraction:

1020+15204201620-\frac{10}{20} + \frac{15}{20} - \frac{4}{20} - \frac{16}{20}

Combine the numerators:

10+15416=15-10 + 15 - 4 - 16 = -15

Thus, the resulting fraction is:

1520-\frac{15}{20}

We simplify 1520-\frac{15}{20} by dividing both the numerator and the denominator by their greatest common divisor, which is 5:

1520=34-\frac{15}{20} = -\frac{3}{4}

Therefore, the solution to the problem is 34 -\frac{3}{4} , which corresponds to choice 2.

Answer

34 -\frac{3}{4}