a = 1
b = 1
20.times do |n|
  a += a * 10
  b += b * 20
  puts "a #{a}. b #{b}. b/a #{b.to_f/a}"
  puts
end

__END__

Output:

a 11. b 21. b/a 1.90909090909091

a 121. b 441. b/a 3.64462809917355

a 1331. b 9261. b/a 6.95792637114951

a 14641. b 194481. b/a 13.2833139812854

a 161051. b 4084101. b/a 25.3590539642722

a 1771561. b 85766121. b/a 48.4127393863378

a 19487171. b 1801088541. b/a 92.4243206466449

a 214358881. b 37822859361. b/a 176.446430325413

a 2357947691. b 794280046581. b/a 336.852276075788

a 25937424601. b 16679880978201. b/a 643.081617962869

a 285311670611. b 350277500542221. b/a 1227.70127065639

a 3138428376721. b 7355827511386641. b/a 2343.79333488946

a 34522712143931. b 154472377739119461. b/a 4474.51454842534

a 379749833583241. b 3243919932521508681. b/a 8542.25504699383

a 4177248169415651. b 68122318582951682301. b/a 16307.9414533519

a 45949729863572161. b 1430568690241985328321. b/a 31133.3427745808

a 505447028499293771. b 30041942495081691894741. b/a 59436.3816605634

a 5559917313492231481. b 630880792396715529789561. b/a 113469.455897439

a 61159090448414546291. b 13248496640331026125580781. b/a 216623.506713293

a 672749994932560009201. b 278218429446951548637196401. b/a 413553.967361741