I'm doing the pascal quiz on rubyquiz.com, but I'm finding that I'm
having trouble assigning a value to my array.

I've assigned it like this:

      pyramid_lvl[level][i] =\
          ( (pyramid[level-1][i-1]).to_i \
          + (pyramid[level-1][i]  ).to_i )

and like this:
      num1 = pyramid[level-1][i-1].to_i
      num2 = pyramid[level-1][i].to_i
      ans = num1+num2
      pyramid_lvl[level][i] = [ans]

Both give me this error message:
undefined method `[]=' for 1:Fixnum (NoMethodError)

Am I getting this problem because I don't understand how arrays work
and it's simply a matter of operations, or am I having some serious
logical problem preventing correctness.