math
posted by Nyla on .
1. Find the LCD of 3/5 and 1/6.
a. 5
b. 6
c. 11
d. 30
2 Add the fractions and write your answer in lowest terms.
2/5 + 1/9
a. 1/15
b. 23/45
c. 3/14
d. 19/45
3. Subtract the fractions and write your answer in lowest terms.
4/5  3/8
a. 1/40
b. 1 7/40
c. 7/10
d. 17/40
4. If Sandy's cookie recipe calls for 1/3 cup of brown sugar and she increases it by 2/9 of a cup, how much brown sugar does she have?
a. 7/9 cup
b. 5/9 cup
c. 4/9 cup
d. 1/9 cup
5. Subtract the fractions and write your answer in lowest terms.
5/8  1/6
a. 30/48
b. 19/24
c. 6/8
d. 6/6
Please help me I can't figure this out. :(

I'll show you the first two.
1. Find the LCD of 3/5 and 1/6.
a. 5
b. 6
c. 11
d. 30
The LCD is the smallest number divisible by both denominators.
Let's look at the multiples of 6:
6, 12, 18, 24, 30. The only one of those numbers that's also divisible by 5 is 30.
2 Add the fractions and write your answer in lowest terms.
2/5 + 1/9
a. 1/15
b. 23/45
c. 3/14
d. 19/45
The least common denominator must be 45.
2/5 = 18/45
1/9 = 5/45
Add the numerators to find your answer.
I'll be glad to check your work and answers for the other three problems. 
here they are
3. a
4. b
5. c
if they r wrong plz tell me the right ones 
help any body

3 is wrong.
4 is right.
I don't think the correct answer is one of your choices for 5.
My answer for 5 is 11/24.
Please make sure you've copied the problem correctly. 
3. 4/5  3/8
the LCD is 40, but you can't just subtract the numerators. "fifths" and "eighths" aren't the came kind of things. In order to make them both into "fortieths" you have to make the denominators equal to 40.
The key to this kind of pronblem is to remember that multiplying by 1 does not change anything. to make 5 into 40, you need to multiply by 8. But to avoid changing the value, you multiply by 8/8 which is just 1.
4/5 * 8/8 = 32/40
3/8 * 5/5 = 15/40
Now everything is expressed in "fortieths", so you can now just subtract. 3215 = 17, so
4/5  3/8 = 32/40  15/40 = 17/40

4. 1/3 + 2/9
1/3 * 3/3 = 3/9
3/9 + 2/9 = 5/9
5. 5/8  1/6
5/8 * 3/3 = 15/24
1/6 * 4/4 = 4/24
15/24  4/24 = 11/24
Hmmm. Not given
However, 5/8 + 1/6 = 19/24. Typo? 
The correct answers are
1.d 30
2.c 5/14
3.b. 5/9
4.d 8/15
5. a 1 1/2, 1 1/9