Answer:
Hi There your answer is 12 Quarters and 8 dimes!
Explanation:
It would be 12 quarters because, a quarter is worth 25 cents and 4 quarters equal a dollar so you would have to do 4*3=12 (since you have to get to 3 dollars) and he would have 8 dimes because, a dime is worth 10 cents and since your already at 3 dollars you would just have to do 8*10 which is 80. So that's how you get $3.80 out of 20 coins!
Your welcome!