Subject :IMO Class : Class 6

A bag contains 1 rupee, 50 paise, 25 paise coins in the ratio 5:6:8. If the total amount is Rs. 420, find the total number of coins.
A : 798
B : 789
C : 978
D : 987
Please help to resolve this problem.
OR
If you have sample questions related to ratios please post the same.