Answer:
you need to learn how to "prime factor" numbers....
primes are 2,3,5,7,11,13,17....
they go on forever. ALL whole numbers can be "broken down" into a bunch of primes multiplied together.
take the fractions (top and bottom) and start dividing them bu the smallest prime, and going up until all the numbers multiplied make the original number...
15 = 3 * 5
24= 2 * 12 = 2 * 2 * 6 = 2* 2* * 2 * 6
thus [tex]\frac{15}{24}[/tex] = [tex]\frac{3 * 5 }{2* 2* 2* 3}[/tex] now just cancel all the SAME numbers from to to bottom
"pair them up" .... in this case only one of the threes in the bottom "takes out" one of the threes in the top
result [tex]\frac{5}{2*2*2 } = \frac{5}{8}[/tex]
~~~~~~~~~~~~~~~~~~~~
[tex]\frac{21}{35}[/tex]
21= 3 * 7
35= 5* 7
[tex]\frac{3*7}{5*7} = \frac{3}{5}[/tex]
Step-by-step explanation: