How do you add/ subtract fractions?

Please explain.

Adding Example:

1/2 + 3/10 = ____

(Please put the answer in a fraction & in its lowest terms)

& Explain to me how you do the problem.

Subtracting Example:

2/3 - 1/2 = ___

(Please put you the answer in a fraction & in it's lowest term)

And explain to me how you did it.

4 Answers

Relevance
  • TrueID
    Lv 4
    9 years ago
    Favorite Answer

    You need to find the common denominator ( the bottem part of the fraction needs to match)

    So you have 1/2, and 3/10, [since 2 does not match 10]

    Multiply 1/2 by 5 (both top and bottem must be multiplied when doing this)

    After multiplying the fraction 1/2 by 5, you get

    so 5/10 + 3/10 = 8/10

    To find the lowest terms, ask yourself what you number can both 8 and 10 be divided by

    you can divided 8 by 2, and you can also divide 10 by 2

    Final answer: 4/5

    2) When dealing with Odd and Even denominator, just multiply the denominator of each other

    (2/3) multiply by 2 both bottem and top

    (1/2) multiply by 3 both bottem and top

    you get 4/6 - 3/6 = 1/6

  • 4 years ago

    a million) 5/8 - a million/4= 5/8-2/8=3/8 2) 5/6 - a million/3= 5/6-2/6=3/6=a million/2 3) 3/4 - a million/3= 3*3/12-a million*4/12=9/12-4/12=5/12 4) 5/12 - 2/12=3/12=a million/4 5) 7/10 - a million/15= 7*3/30-a million*2/30=21/30-2/30=19/30 u might desire to discover on the backside of the "new" fraction the smaller sort which would be divided via the two the bottoms of the two (or greater) fractions that u upload or subtract, as u c, case in point, interior the num 3 the smaller num "obtainable" is 12 so 12 (the backside of the fraction u might have) / 4(the backside of the 1st fraction)=3 that u moltiply with the three that u already have 3*3/12=9/12 in certainty 9/12 is an identical element than 3/4... than u do an identical element with the different fraction so as that u could have 2 fraction with an identical backside that u can basically subtract or upload.

  • 9 years ago

    first find LCD (lease common denominator) whether its add/subtract

    first fraction has a denom of 2 & second has a denom of 10

    2 has factors of 1 & 2

    10 has factors of 1, 2 & 5

    the least common factors of both is 1, 2 & 5

    their least common denominator is the multiplication of 1, 2 & 5 = 10

    What is missing for the LCD of the first fraction? 1 & 2...needs 5

    What is missing for the LCD of the second fraction? 1, 2 & 5...needs nothing

    Okay remember in grade school the multiplication tables, specifically ones "1"

    where 1 times any number is still that number? no change! 1*1 = 1, 1*2 = 2, and so on

    Okay 5 was missing from the first fractions denom...so multiply it by 5, but whatever we

    do to the denom of that fraction must also be done to its numerator, ie multiply it also by 5 which would be reduced 5/5 = 1 which is legit 1*half = half

    5*1/(5*2) + 3/10 = 5/10 + 3/10

    now that we have the same denominator we have

    (5 + 3)/10 = 8/10

    not in lowest terms, reduce to 4/5

    LCD = 6

    2/3 - 1/2 = 2*2/(2*3) - 3*1/(3*2) = 4/6 - 3/6 = (4 - 3)/6 = 1/6

  • Anonymous
    9 years ago

    for adding you make the denominator the same.

    ex:

    1/2 + 3/10

    you make these "addable" by:

    1/2 = 5/10

    then:

    5/10+3/10= 8/10

    simplify:

    8/10=4/5

    answer:

    4/5.

    I forgot how you subtract xC

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