Question 119375
john traveled 40 mph to his friends house
on the return trip back home he traveled 45 mph
It took him 4 hrs round trip
Question: What was the total distance traveled?
:
Let d = distance one way:
: 
Write a time equation; Time = dist/speed
;
Time at 40mph + time at 45 mph = 4 hrs
:
{{{d/40}}} + {{{d/45}}} = 4
:
Multiply equation by; 40*45 = 1800; gets rid of the denominators:
1800*{{{d/40}}} + 1800*{{{d/45}}} = 1800(4)
:
45d + 40d = 7200
:
85d = 7200
d = {{{7200/85}}}
d = 84.7 miles, one way distance
:
2*84.7 = 169.4 total miles
:
:
Check our solution:
{{{84.7/40}}} + {{{84.7/45}}} =
2.1175 + 1.88 = 3.997 ~ 4 hrs