To divide fractions turn the second fraction upside down so in this case the second fraction is 9/16 so we turn it upside down and it becomes 16/9 and then you just multiply 3/8 times 16/9
3 times 16 is 48 and 8 times 9 is 72 so you get 48/72. Then you can simplify and you get 2/3 so the answer is 2/3