algebra
posted by john .
rachel allows herself one hour to reach a sales appointment 50 miles away. after she has driven 30 miles, she realizes that she must increase her speed by 15mph in order to arrive on time. what was her speed for the first 30 miles?

Rachel allows herself one hour to reach a sales appointment 50 miles away. after she has driven 30 miles, she realizes that she must increase her speed by 15mph in order to arrive on time. what was her speed for the first 30 miles?
The time to drive the first 30 miles is T1 = 30/V1.
The time to drive the last 20 miles is T2 = 20/(v1 + 15)
wHAT DO YOU KNOW ABOUT t1 + t2? 
that it equals 60 minutes?