Jane rode a 50 mike bike course in four hours . She averaged 15 mph over part of the course and the rest 10 mph. How many hours did she ride at 15 mph?

Question

Four times he smaller of two consecutive whole numbers minus three times the larger number is 4. What is the smaller number .?

Answer 1

Total distance=50=15t+10(4-t) where t is the time travelled at 15mph and 4-t the time travelled at 10mph.

So 50=15t+40-10t, 10=5t, so t=2 hours.

(She rode 15×2=30 miles at 15mph and 10×2=20 miles at 10mph. 30+20=50 miles.)

 

Let n and n+1 be the numbers.

4n-3(n+1)=4, 4n-3n-3=4, n=7, the smaller number.