im assuming that you mean 3/8 and 13/5
so you find the LCM of 8 and 5 which is 40
3/8 = 15/40
13/5 = 104/40
Answer:
Their least common denominator is 90.
Step-by-step explanation:
Given : Jaime has two fractions, [tex]\frac{3}{18}[/tex] and [tex]\frac{13}{15}[/tex], that he needs to compare. He knows he will not be able to tell which is bigger until they have been rewritten with the same denominator.
To find : Which of the following shows both of these fractions rewritten with their least common denominator?
Solution :
The two fractions, [tex]\frac{3}{18}[/tex] and [tex]\frac{13}{15}[/tex] to compare we make denominator same.
Taking LCM of denominator 15 and 18,
2 | 15 18
3 | 15 9
3 | 5 3
5 | 5 1
| 1 1
[tex]LCM(15,18)=2\times 3\times 3\times 5[/tex]
Now make denominator same,
Multiply and divide [tex]\frac{3}{18}[/tex] by 5,
[tex]\frac{3\times 5}{18\times 5}=\frac{15}{90}[/tex]
Multiply and divide [tex]\frac{13}{15}[/tex] by 6,
[tex]\frac{13\times 6}{15\times 6}=\frac{78}{90}[/tex]
Now, Comparing the fractions numerator 78 > 15
i.e. [tex]\frac{78}{90}>\frac{15}{90}[/tex]
So, [tex]\frac{13}{15}>\frac{3}{18}[/tex]
Therefore, Their least common denominator is 90.
