Question 1024693
Let {{{ s }}} = the normal speed to get to airport on time
Let {{{ t }}} = time in hrs to get to airport with decreased speed
(1) {{{ 39 = s*(3/4) }}}
(2) {{{ 39 = ( s - 1/4 )*t }}}
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(2) {{{ 39 = s*t - (1/4)*t }}}
(2) {{{ 156 = 4s*t - t }}}
and
(1) {{{ 39 = s*(3/4) }}}
(1) {{{ 156 = 3s }}}
(1) {{{ s = 52 }}}
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Plug this result into (2)
(2) {{{ 156 = 4s*t - t }}}
(2) {{{ 156 = 4*52*t - t }}}
(2) {{{ 156 = 208t - t }}}
(2) {{{ 156 = 207t }}}
(2) {{{ t = .7536 }}}
{{{ .7536*60 = 45.217 }}}
{{{ .217*60 = 13 }}}
The time home from airport will be 
45 min and 13 sec
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check:
(2) {{{ 39 = ( s - 1/4 )*t }}}
(2) {{{ 39 = (52 - .25 )*.7536 }}}
(2) {{{ 39 = 51.75*.7536 }}}
(2) {{{ 39 = 38.998 }}}
Error due to rounding off