Question

A recipe for 3 servings calls for 2 grams of saffron. How many milligrams of saffron are needed for 6 servings?

Answer 1

Since there are 

2 grams od saffron in 3 servings just double the servings

so for 6 servings you will need 4 grams of saffron

i hope it makes since 

Answer 2

if he used 2 to make 3 then he would have to use 4 to make 6

if the amount made is doubled then you must double the other number too.