Question 717863
Let {{{ t }}} = the time in hours from when they both
start running to when you catch your friend
Let {{{ d }}} = the distance that you have to travel until
you catch your friend
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Your equation:
(1) {{{ d = 5t }}}
Your friend's equation:
(2) {{{ d - 2 = 4t }}}
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Substitute (1) into (2)
(2) {{{ 5t - 2 = 4t }}}
(2) {{{ t = 2 }}}
In 120 minutes, you will catch your friend
check:
(1) {{{ d = 5t }}}
(1) {{{ d = 5*2 }}}
(1) {{{ d = 10 }}} mi
and
(2) {{{ d - 2 = 4t }}}
(2) {{{ d - 2 = 4*2 }}}
(2) {{{ d = 8 + 2 }}}
(2) {{{ d = 10 }}} mi
OK