Question 627125
Driving 51 mi/hr average:
(1) {{{ d = 51t }}}
Driving 60 mi/hr average:
(2) {{{ d = 60*( t - 3 ) }}}
------------------------
Substitute (1) into (2)
(2) {{{ 51t = 60*( t - 3 ) }}}
(2) {{{ 51t = 60t - 180 }}}
(2) {{{ 9t = 180 }}}
(2) {{{ t = 20 }}}
and
(1) {{{ d = 51t }}}
(1) {{{ d = 51*20 }}}
(1) {{{ d = 1020 }}}
The distance is 1,020 mi
check:
(2) {{{ d = 60*( t - 3 ) }}}
(2) {{{ 1020 = 60*( 20 - 3 ) }}}
(2) {{{ 1020 = 60*17 }}}
(20 {{{ 1020 = 1020 }}}
OK