if your circumstance is 35pi then the formula would be c=35pi and to find that it would have been c=2 pi r. to find the diameter it would be d=c/pi. so it would be d=35pi/pi. the pi's would cancel out and you have 35 as the diameter and 17.5 as the radius
c=2 pi r
c= 2 pi 17.5
i hoped this , i am not sure but this is what i think
3 dimes, 9 pennies, and 5 nickels
call the number of dimes d. then, we will have 3d pennies and d + 2 nickels. the value for each group is 10d, 3d, and 5d + 10. add these to get 18d + 10. this is equal to 64 cents, as stated in the question. so, setting these equal, we get that d = 3, and there are 3 dimes, 9 pennies, and 5 nickels.