GCSE Probability Given for 2 successive withdrawals from Red and Blue find the number of Blue Chips

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There are some red counters and some blue counters in a bag
The ratio of red counters to blue counters is 3:1
Two counters are removed at random
The probability that both the counters taken are blue is 1/20
Work how many counters were in the bag before any counter were removed.

[NimraKhan-jmpw]

I have a similar question like that. I need help in that question. The question is:
There are red counters and blue counters. Ratio of red counters to blue counters is 4:1. Two counters are removed at random. The probability that both are red is 22/35. How many blue counters are there?