Divide 100 by 5 to find the unit rate, which is 20 roses for every flower arrangement. Multiply 20 by 4 to find how many roses the florist would use for 4 arrangements.
The answer is 256pi if you have a calculator, and it says to put it in 3.14 for pi, do the same steps I show here, but instead of pi, you would put 3.14. But I hope this helps you