ruby.rb

def calc numbers, ops
  expression = numbers.zip(ops).flatten.compact
  # need some bodmas action

  while expression.include?(:/)
    result = [expression[expression.index(:/) - 1].to_f,expression[expression.index(:/) + 1].to_f].inject :/
    expression.delete(expression[expression.index(:/) - 1])
    expression.delete(expression[expression.index(:/) + 1])
    expression[expression.index(:/)] = result
  end

  while expression.include?(:*)
    result = [expression[expression.index(:*) - 1].to_f,expression[expression.index(:*) + 1].to_f].inject :*
    expression.delete(expression[expression.index(:*) - 1])
    expression.delete(expression[expression.index(:*) + 1])
    expression[expression.index(:*)] = result
  end

  while expression.include?(:+)
    result = [expression[expression.index(:+) - 1].to_f,expression[expression.index(:+) + 1].to_f].inject :+
    expression.delete(expression[expression.index(:+) - 1])
    expression.delete(expression[expression.index(:+) + 1])
    expression[expression.index(:+)] = result
  end

  while expression.include?(:-)
    result = [expression[expression.index(:-) - 1].to_f,expression[expression.index(:-) + 1].to_f].inject :-
    expression.delete(expression[expression.index(:-) - 1])
    expression.delete(expression[expression.index(:-) + 1])
    expression[expression.index(:-)] = result
  end
  result
end


p calc [1, 2, 3], [:/, :/]