Question 271003
write equations for each trip
(1) {{{d[1] = r[1]*t[1]}}}
(2) {{{d[2] = r[2]*t[2]}}}
given:
{{{d[1] = d[2]}}} (call it {{{d}}})
{{{r[1] = 520}}} mi/hr
{{{r[2] = 600}}} mi/hr
{{{t[2] = t[1] - 2/3}}} hr (40 min is 2/3 hr)
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(1) {{{d = 520*t[1]}}}
(2) {{{d = 600*(t[1] - 2/3)}}}
they both equal {{{d}}}, so
{{{520t[1] = 600t[1] - 400}}}
{{{80t[1] = 400}}}
{{{t[1] = 5}}} hrs
And, from (1)
{{{d = 520*t[1]}}}
{{{d = 520*5}}}
{{{d = 2600}}} mi
They are 2600 miles from eachother
check answer:
(2) {{{d = 600*(t[1] - 2/3)}}}
{{{d = 600*(4 + 1/3)}}}
{{{d = 2400 + 200}}}
{{{d = 2600}}} mi
OK