Question 1129422
Let {{{ d }}} = distance traveled on the winding road
{{{ 384 - d }}} = distance traveled on level road
Let {{{ s }}} = the average speed on the winding road
{{{ s + 20 }}} = the average speed on the level road
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Equation for winding road:
(1) {{{ d = s*2 }}}
Equation for level road:
(2) {{{ 384 - d = ( s + 20 )*6 }}}
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(2) {{{ 384 - d = 6s + 120 }}}
Plug (1) into (2)
(2) {{{ 384 - 2s = 6s + 120 }}}
(2) {{{ 8s = 264 }}}
(2) {{{ s = 33 }}}
and
{{{ s + 20 = 53 }}}
The speed on level road was 53 mi/hr
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check:
(1) {{{ d = 2*33 }}}
(1) {{{ d = 66 }}}
and
(2) {{{ 384 - d = ( s + 20 )*6 }}}
(2) {{{ 384 - d = 6s + 120 }}}
(2) {{{ 384 - d = 6*33 + 120 }}}
(2) {{{ d = 384 - 198 - 120 }}}
(2) {{{ d = 66 }}}
OK