Question

A car is traveling on a small highway and is either going 55 miles per hour or 35 miles per hour, depending on the speed limits, until it reaches its destination 200 miles away. Letting x represent the amount of time in hours that the car is going 55 miles per hour, and y being the time in hours that the car is going 35 miles per hour, an equation describing the relationship is: 55x+35y=200

A: If the car spends 2.5 hours going 35 miles per hour on the trip, how long does it spend going 55 miles per hour?

B: If the car spends 3 hours going 55 miles per hour on the trip, how long does it spend going 35 miles per hour?

C: If the car spends no time going 35 miles per hour, how long would the trip take? Explain your reasoning.

Answer 1

A. The car spends 2.05 hours going 55 miles per hour

B. The car spends 1 hour going 35 miles per hour

C. The trip takes 3.6 hour

Explanation:

The equation is

55x+35y=200

Let's solve A

We know the car spends 2.5 hours going 35 miles per hour on the trip, so we put 2.5 in for y and solve for x

55x+35(2.5) = 200

55x + 87.5 = 200

55x = 112.8

x = 2.05 hours going 55 miles per hour

So, the car spends 2.05 hours going 55 miles per hour

Let's solve B

55(3)+35y=200

165 + 35y = 200

35y = 35

y = 1 hour

So, the car spends 1 hour going 35 miles per hour

Let's solve C

We know the car spends no time going 35 miles per hour, so we put 0 in for y and solve for x

55x+35(0)=200

55x = 200

x = 3.6 hours

So, the trip takes 3.6 hour