You would need to set of a ratio/proportion.
160/100 =24/x
you can reduce and make it to 8/5 = 24/x
the cross multiply 8x = 5(24)
so now it becomes 8x = 120
then we get the variable by itself by dividing by 8 on both sides, x = 120/8
so x=15, meaning 15 milligrams are recommended