Question 22908
LET AMY'S SPEED BE X MPH….TIME TO TRAVEL 450 MILES=450/X HRS.
IF CAR GOES 15 MPH FASTER SPEED = X+15…..TIME TO TRAVEL=450/(X+15)
THIS TIME IS 1 HOUR LESS.SO…450/X-450/(X+15)=1…MULTIPLYING BY LCM X(X+15)
450{X+15-X)=X(X+15)=450*15=6750=X^2+15X
X^2+15X-6750=0=X^2+90X-75X-6750=X(X+90)-75(X+90)=(X-75)(X+90).HENCE X=75….B IS THE ANSWER.