Last month Maria hiked the 5-mile mountain trail a number of times and she hiked the 10-mile canal trail several times. Let x represent the number of times she hiked the 5-mile trail, and let y represent the number of times she hiked the 10-mile trail. If she hiked a total of 90 miles, which equation can be used to find the number of times Maria hiked each trail?

x + y = 90

5x - 10y = 90

90 - 10y = 5x

90 + 10y = 5x

It would be the third equation.

If we set it up without looking at the answers we would get 5x + 10y = 90

None of the options are exactly like this so you have to rearrange them so that you select the correct one.

We can eliminate the first one immediately because it doesn't have the 5 and 10.

The second one is subtracting the 10 mile hikes.

the last two don't have the x and y on the same side so they have to be re-written.

The fourth one yields a negative 10 again.

3 is our answer.