Question 751119
Let {{{ t }}} = the time in hours it takes blue car to catch red car
Let {{{ d }}} = the distance in miles blue car has to travel to catch red car
-----------------
Blue car's equation:
(1) {{{ d =70t }}}
Red car's equation:
(2) {{{ d - 40 = 50t }}}
------------------
Substitute (1) into (2)
(2) {{{ 70t - 40 = 50t }}}
(2) {{{ 20t = 40 }}}
(2) {{{ t = 2 }}}
-------------
(1) {{{ d = 70t }}}
(1) {{{ d = 70*2 }}}
(1) {{{ d = 140 }}}
---------------
a). It takes 2 hours for the blue car to catch the red car
b). They traveled 140 miles from the starting point when the blue car catches the red car
---------------
check answer:
(2) {{{ d - 40 = 50t }}}
(2) {{{ 140 - 40 = 50*2 }}}
(2) {{{ 100 = 10-0 }}}
OK