Respuesta :
You need to make the denominators in the equation the same to add or subtract fractions. Pick a denominator both can multiply up to. ( this is called the least common denominator. Look it up if your unsure) so if the denominators were 2 and 3, multiply them so they both are 6. You have to multiple the numerator then too ( what you do to the bottom of the fraction, you must also do to the top) so if your fraction was 1/3 and you multiplied 3 by 2 to get 6, you would also have to multiple the 1 by 2 so then your fraction is 2/6. Once you have done that you can subtract the numerators like normal, just keep the denominators the same. So 2/6 - 1/6 = 1/6. When you have equations with mixed numbers, turn those into improper fractions first. Ex. 1 1/4 you would multiply the one on the outside of the fraction by the denominator and then add the numerator. 1 1/4 = 5/4. Then add or subtract like normal. Remember to keep your denominator the same ALWAYS when subtracting and adding fractions. Hope this helps!
Answer:
1. -9/20
2. 1 7/12
3. -4 1/3
Step-by-step explanation:
When adding and subtracting fractions with unlike denominators, you must first make them like denominators. To do this we must:
1. Find the Least Common Multiple of the denominators (which is called the Least Common Denominator).
2. Change each fraction (using equivalent fractions) to make their denominators the same as the least common denominator.
3. Then add (or subtract) the fractions, as we wish!
The easiest way to this is by multiplying the denominators. Remember that whatever you do to the bottom, you also do to the top
1. -5/4 +4/5
if we multiply 4 and 5, we get 20. Our denominator will be 20 before we simplify.
our new equation is going to be -25/20 + 16/20. Now we can add these together to get an answer of -9/20. Which is in the simplist form.
One more thing: to make a mixed number an improper fraction, you multiply the whole number by the denominator, and add the numerator.
1X4=4
4+1=5
The improper fraction is 5/4.
To make a Whole number a fraction, multiply the number by the denominator
-5x3=15
The improper is -15/3.
To go from an improper to a mixed, divide the numerator by the denominator. The remainders are going to be the fraction attached.
