Let the number be X
then given that (2/5)×number=8
that is (2/5)×x=8
make x in left side of = and all othet in the right side of =
so x=(5/2)×8
because when numerator goes to other side of =,then it becomes denominator and denominator becomes numerator
(5/2)×8=20
so the number is 20
please like if u r satisfued