Exhibit No. 12. Mountain Fuel Supply Company Ratio of Earnings to Fixed Charges 12 Months Ended June 30, 1996 1997 (Dollars in Thousands) Earnings Income before income taxes $40,208 $45,639 Plus debt expense 16,594 17,271 Plus allowance for borrowed funds used during construction 349 257 Plus interest portion of rental expense 296 170 $57,447 $63,337 Fixed Charges Debt expense $16,594 $17,271 Plus allowance for borrowed funds used during construction 349 257 Plus interest portion of rental expense 296 170 $17,239 $17,698 Ratio of Earnings to Fixed Charges 3.33 3.58