grid-calculator.rb

def calculate_grid(options)
    results = []
    (0..options[:width]).each do |n|
        gutter = n.to_f
        col = (options[:width] - (gutter * (options[:cols] + 1))) / options[:cols]
        break if col < 0
        results << "col: #{col.to_i}px / gutter: #{gutter.to_i}px" if col % 1 == 0
    end
    results
end

puts calculate_grid cols: 7, width: 1100