Question 475299
Let {{{a}}} = miles that he ran
Let {{{b}}} = miles that he walked
given:
(1) {{{ a + b = 68 }}}
(2) {{{ a/8 + b/4 = 12 }}}
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Multiply both sides of (2) by {{{8}}}
(2) {{{ a + 2b = 96 }}}
Subtract (1) from (2)
(2) {{{ a + 2b = 96 }}}
(1) {{{ -a - b = -68 }}}
{{{ b = 28 }}}
and
(1) {{{ a + b = 68 }}}
(1) {{{ a + 28 = 68 }}}
(1) {{{ a = 68 - 28 }}}
(1) {{{ a = 40 }}}
Ludwig ran 40 miles and walked 28 miles
check answer:
(2) {{{ a/8 + b/4 = 12 }}}
(2) {{{ 40/8 + 28/4 = 12 }}}
(2) {{{ 5 + 7 = 12 }}}
(2) {{{ 12 = 12 }}}
OK