tom traveled 250mls. for most of the trip he averaged 70mph

Question

For a period of time he was slowed to 10mph.  If the total time was 7hrs, how many miles did he travel at the reduced speed?

Answer 1

assuming mls. is supposed to be miles...usually abbreviated as just m

 

first we need to solve this system of equations:

70x+10y=250

x+y=7

 

using the second equation we get that x=7-y

 

substitute x=7-y into the first equation

 

70(7-y)+10y=250

 

490-70y+10y=250

 

-60y=-240

 

y=240/60=4

 

now we know he traveled at 10mph for 4 hours

 

that is 10*4=40 

 

so he traveled at 10mph for 40 miles