Question 656228
Call cost of 1 CD {{{ x }}}
Call cost of 1 cassette tape {{{ y }}}
Call cost of 1 video cassette {{{ z }}}
given:
(1) {{{ 3x + 3y = 4z }}}
(2) {{{ n*x + n*y + n*z = 28z }}}
From (1)
(1) {{{ x + y = (4/3)*z }}}
From (2)
(2) {{{ n = (28z) / ( x + y + z ) }}}
(2) {{{ n = (28z) / ((4/3)*z + z ) }}}
(2) {{{ n = 28 / (7/3) }}}
(2) {{{ n = 12 }}}
She can buy 12 video cassettes
Hope I got it