Question 429790
Let {{{a}}} = pounds of soy meal needed
Let {{{b}}} = pounds of corn meal needed
given:
(1) {{{ ( .14a + .07b ) / 280 = .11 }}}
(2) {{{ a + b = 280 }}}
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(1) {{{ .14a + .07b  = .11*280 }}}
(1) {{{ .14a + .07b  = 30.8 }}}
(1) {{{ 14a + 7b  = 3080 }}}
Multiply both sides of (2) by {{{7}}}
and subtract (2) from (1)
(1) {{{ 14a + 7b  = 3080 }}}
(2) {{{ -7a - 7b = -1960 }}}
{{{ 7a = 1120 }}}
{{{ a = 160 }}}
and, since
(2) {{{ a + b = 280 }}}
{{{ 160 + b = 280 }}}
{{{ b = 120 }}}
160 pounds of soy meal is needed
120 pounds of corn meal is needed