Why is a sales tax a regressive tax?

Verizon communications, inc., provides the following footnote relating to its leasing activities in its 10-k report. the aggregate minimum rental commitments under noncancelable leases for the periods shown at december 31, 2010, are as follows: years (dollars in millions) capital leases operatingleases 2011 $97 $1,898 2012 74 1,720 2013 70 1,471 2014 54 1,255 2015 42 1,012 thereafter 81 5,277 total minimum 418 $ 12,633 rental commitments less interest and (86) executory costs present value of 332 minimum lease payments less current (75) installments long-term obligation $257 at december 31, 2010 (a) confirm that verizon capitalized its capital leases using a rate of 7.4 %. (b) compute the present value of verizon's operating leases, assuming an 7.4% discount rate and rounding the remaining lease term to 3 decimal places. (use a financial calculator or excel to compute. do not round until your final answers. round each answer to the nearest whole number.)