Passing return value into another method - ruby

Question

I am starting with an array of letters:
letters = %w[c s t p b l f g d m
y o u i h t r a e l
o t l a e m r s n i
m a y l p x s e k d]
Passing them, finding all combinations that return an array like this ["cstp", "cstb", "cstl"], this is a shortened example.
def combinations(letters)
combos = letters.combination(4)
combos.collect do |letter_set|
letter_set.join(",").gsub("," ,"")
end
end
I am trying to figure out how to pass the return value of combinations into start_wtih_letter_c. Do I have to pass a block like &block? I tried various things that keep saying wrong number of arguments.
def start_with_letter_c(pass the return value)
combinations.select {|word| word.match(/^ca/) }
end

Answer 1

Here you go, no errors:
letters = %w[c s t p b l f g d m
y o u i h t r a e l
o t l a e m r s n i
m a y l p x s e k d]
def combinations(letters)
combos = letters.combination(4)
combos.collect do |letter_set|
letter_set.join(",").gsub("," ,"")
end
end
def start_with_letter_c(combinations)
combinations.select {|word| word.match(/^ca/) }
end
start_with_letter_c(combinations(letters))
# => ["cael", "caeo", "caet", "cael", "ca ...and so on

Answer 2

I would write something like this:
letters = %w[c s t p b l f g d m
y o u i h t r a e l
o t l a e m r s n i
m a y l p x s e k d]
def combinations(letters)
letters.combination(4).map(&:join)
end
def start_with_letter_c(combinations)
combinations.select { |word| word.start_with?('ca') }
end
start_with_letter_c(combinations(letters))