Question 718820
(1) {{{ m + n = 10 }}}
(2) {{{ 3m - 2n = 15 }}}
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(1) {{{ n = 10 - m }}}
Substitute this result into (2)
(2) {{{ 3m - 2*( 10 - m ) = 15 }}}
(2) {{{ 3m - 20 + 2m = 15 }}}
(2) {{{ 5m - 20 = 15 }}}
(2) {{{ 5m = 35 }}}
(2) {{{ m = 7 }}}
and, since
(1) {{{ m + n = 10 }}}
(1) {{{ 7 + n = 10 }}}
(1) {{{ n = 3 }}}
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check:
3 times the larger is 21
twice the smaller is 6
{{{ 21 - 6 = 15 }}}
OK