Question 772234
{{{.1x + .9y = -4.3 }}}
{{{ .5x - .4y = 3 }}}
I would multiply both sides of both
equations by {{{ 10 }}}
(1) {{{ x + 9y = -43 }}}
(2) {{{ 5x - 4y = 30 }}}
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Solve (1) for {{{x}}}
(1) {{{ x = -9y - 43 }}}
Substitute this result into (2)
(2) {{{ 5*( -9y -43 ) - 4y = 30 }}}
(2) {{{ -45y - 215 - 4y = 30 }}}
(2) {{{ -49y = 245 }}}
(2) {{{ y = -245/49 }}}
(2) {{{ y = -5 }}}
and
(1) {{{ x = -9*( -5 ) - 43 }}}
(1) {{{ x = 45 - 43}}}
(1) {{{ x = 2 }}}
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check:
{{{ .5x - .4y = 3 }}}
{{{ .5*2 - .4*(-5) = 3 }}}
{{{ 1 + 2 = 3 }}}
{{{ 3 = 3 }}}
OK