Question 1138072
Let {{{ a }}} = ml of 100% vinegar needed
Let {{{ b }}} = ml of Italian dressing needed
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(1) {{{ a + b = 210 ml }}}
(2) {{{ a + .16b = .48*210 }}}
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(2) {{{ a + .16b = 100.8 }}}
(2) {{{ 100a + 16b = 10080 }}}
(2) {{{ 25a + 4b = 2520 }}}
and
(1) {{{ 4a + 4b = 840 }}}
Subtract (1) from (2)
(2) {{{ 25a + 4b = 2520 }}}
(1) {{{- 4a - 4b = -840 }}}
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{{{ 21a = 1680 }}}
{{{ a = 80 }}}
and
(1) {{{ 80 + b = 210 }}}
(1) {{{ b = 130 }}}
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80  ml of 100% vinegar are needed
130 ml of Italian dressing are needed
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check:
(2) {{{ a + .16b = 100.8 }}}
(2) {{{ 80 + .16*130 = 100.8 }}}
(2) {{{ 80 + 20.8 = 100.8 }}}
(2) {{{ 100.8 = 100.8 }}}
OK