Question 1095810
Let {{{ x }}} = the cost of 1 marker
Let {{{ y }}} = the cost of 1 notebook
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(1) {{{ 12x + 15y = 2000 }}}
(2) {{{ 3x = 6y }}}
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Divide both sides of (2) by {{{3 }}}
(2) {{{ x = 2y }}}
Substitute (2) into (1)
(1) {{{ 12*(2y) + 15y = 2000 }}}
(1) {{{ 24y + 15y = 2000 }}}
(1) {{{ 39y = 2000 }}}
(1) {{{ y = 51.28 }}}
Plug this result back into (2)
(2) {{{ x = 2*51.28 }}}
(2) {{{ x = 102.56 }}}
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One marker costs 102.56
One notebook costs 51.28
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check:
(1) {{{ 12x + 15y = 2000 }}}
(1) {{{ 12*102.56 + 15*51.28 = 2000 }}}
(1) {{{ 1230.72 + 769.2 = 2000 }}}
(1) {{{ 1999.92 }}}
OK -error due to rounding off