Question 1096627
Let {{{ a }}} = ounces of 5% chocolate milk needed
Let {{{ b }}} = ounces of 10% chocolate milk needed
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(1) {{{ a + b = 10 }}}
(2) {{{ ( .05a + .1b ) / 10 = .08 }}}
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(2) {{{ .05a + .1b = .8 }}}
(2) {{{ 5a + 10b = 80 }}}
(2) {{{ a + 2b = 16 }}}
Subtract (1) from (2)
(2) {{{ a + 2b = 16 }}}
(1) {{{ -a - b = -10 }}}
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{{{ b = 6 }}}
and
(1) {{{ a + 6 = 10 }}}
(1) {{{ a = 4 }}}
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4 ounces of 5% chocolate milk are needed
6 ounces of 10% chocolate milk are needed
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check:
(2) {{{ ( .05a + .1b ) / 10 = .08 }}}
(2) {{{ ( .05*4 + .1*6 ) / 10 = .08 }}}
(2) {{{ ( .2 + .6 ) / 10 = .08 }}}
(2) {{{ .8 = .8 }}}
OK