Question 251788
{{{d}}} = cost of 1 dvd
{{{t}}} = cost of 1 tape
given:
(1) {{{2d + 3t = 31}}}
(2) {{{3d + 2t = 29}}}
Multiply (1) by {{{3}}} and (2) by {{{2}}}
and subtract (2) from (1)
(1) {{{6d + 9t = 93}}}
(2) {{{-6d - 4t = -58}}}
{{{5t = 35}}}
{{{t = 7}}}
and, since
{{{2d + 3t = 31}}}
{{{2d + 3*7 = 31}}}
{{{2d = 31 - 21}}}
{{{2d = 10}}}
{{{d = 5}}}
Each tape cost $7 and each dvd costs $5