Pre-Algebra : Addition and Subtraction
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Example Question #51 : Addition And Subtraction
Solve:
When two minus signs meet, it becomes a plus sign. We add normally. Answer is 
Example Question #52 : Addition And Subtraction
Solve:
When we have two negative numbers present, we treat as an addition problem but add a minus sign in the end. Answer is 
Example Question #53 : Addition And Subtraction
Write solution as an improper fraction.
When adding or subtracting fractions, you must find the common denominator. This is best done by finding the least common multiple of the denominators, in this case 5 and 3. What is the lowest number that is divisible by both 5 and 3? Often, the easiest solution is to multiply the denominators together. This works most often with single digit numbers. Anything larger and you will have to find the least common multiple another way.
The LCM of 5 and 3 is 15 (5 x 3). Now you know that both fractions must have 15 on the bottom. Now, to convert 4/5 to ?/15, you must recognize how many times 5 goes into 15 (3), and multiply the numerator by that number. Therefore:
Do the same with the other side.
Now that the denominators match, all that's left is to add the numerators together.
This solution is already an improper fraction (the numerator is larger than the denominator), therefore you may leave the fraction as is.
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