A certain recipe calls for 2 /3 cup of flour. A chef is making an amount that is 3 /5 of the recipe. How much flour should the chef use?

If he is making 3/5 of the recipe, then he needs 3/5 of the flour.

3/5 of 2/3 ... " of " means multiply

3/5 * 2/3 = 6/15 which reduces to 2/5

So the chef should use 2/5 cups of flour <==