Question 1098936
Let {{{ a }}} = number of jeans sold on friday ( also sat )
Let {{{ b }}} = number of shirts sold on friday ( also sat )
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(1) {{{ 25a + 18b = 441 }}}
(2) {{{ 20a + 20b = 420 }}}
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(2) {{{ a + b = 21 }}}
(2) {{{ b = 21 - a }}}
Plug (2) into (1)
(1) {{{ 25a + 18*( 21 - a ) = 441 }}}
(1) {{{ 25a + 378 - 18a = 441 }}}
(1) {{{ 7a = 63 }}}
(1) {{{ a = 9 }}}
and
(2) {{{ b = 21 - 9 }}}
(2) {{{ b = 12 }}}
9 jeans were sold on friday ( also sat )
12 shirts were sold on friday ( also sat )