SOLUTION: Because of traffic Maria could average only 40 km/h for the first 20% of her trip, but she averaged 75 km/h for the whole trip. What was her average speed for the last 80% of her

Algebra ->  Percentage-and-ratio-word-problems -> SOLUTION: Because of traffic Maria could average only 40 km/h for the first 20% of her trip, but she averaged 75 km/h for the whole trip. What was her average speed for the last 80% of her       Log On


   

Question 72142This question is from textbook Algebra and Trigonometry: Structure and Method
: Because of traffic Maria could average only 40 km/h for the first 20% of her trip, but she averaged 75 km/h for the whole trip. What was her average speed for the last 80% of her trip? This question is from textbook Algebra and Trigonometry: Structure and Method

Answer by checkley75(3666) About Me  (Show Source):
You can put this solution on YOUR website!
40*.2+x*.8=75
8+.8x=75
.8x=75-8
.8x=67
x=67/.8
x=83.75 km/h
proof
.2*40+.8*83.75=75
8+67=75
75=75