Question 935940
(1) {{{ x + y = 21 }}}
(2) {{{ 2x + 3y = 53 }}}
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Multiply both sides of (1) by {{{ 2 }}}
and subtract (1) from (2)
(2) {{{ 2x + 3y = 53 }}}
(1) {{{ -2x - 2y = -42 }}}
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{{{ y = 11 }}}
and
(1) {{{ x + y = 21 }}}
(1) {{{ x + 11 = 21 }}}
(1) {{{ x = 10 }}}
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There are 10 rooms with 2 beds
There are 11 rooms with 3 beds
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check:
(2) {{{ 2x + 3y = 53 }}}
(2) {{{ 2*10 + 3*11 = 53 }}}
(2) {{{ 20 + 33 = 53 }}}
(2) {{{ 53 = 53 }}}
OK