how you multoply 5 2/7 x 5/8 x 3 1/2 write the answer in simplest form

First of all you have to change all mixed fractions to improper fractions, mixed fractions are useless in calculations.

Then multiply your numerators together and multiply your denominators together.
Check to see if you can reduce your fraction to lowest terms.

For some "mathemagics" find the key "a b/c" on your scientific calculator.

it can be used to reduce your fractions to lowest terms.
e.g. 18/24 = ???

enter 18, press a b/c, enter 24, then press =
WOW