A cyclist rides at 15 km/h. How many hours does it take to ride 75 km?

Step by step, with the reason for every step · Word problems part 2 · Algebra 1

Step by step

The question

Question: A cyclist rides at 15 km/h.

How many hours does it take to ride 75 km?

1 Find what we know

What do we know?

The cyclist goes 15 km in each hour.

The trip is 75 km.

What do we want?

How many hours.

2 Name the unknown

We don't know how many hours.

So we call it x.

x = number of hours

How far we go: speed times time.

15 km/h means 15 km in each hour.

distance = speed × time

3 Write the equation

In words: speed times time makes the distance.

15x = 75

So the equation is 15x = 75.

Now we solve it.

15x = 75

4 Remove the 15

15x means 15 times x.

We want just x.

To remove times 15, we divide by 15.

We do it on both sides, so they stay equal.

15x15 = 7515

15 divided by 15 is 1.

So just x is left.

75 divided by 15 is 5.

7515 = 5

So x = 5!

x = 5

5 Answer the question

So it takes 5 hours.

6 Check

Let's check in the story.

5 hours at 15 km/h: 5 times 15 is 75 km, like the story says.

So the answer is right!

5 × 15 = 75 km

Let's look back.

First: find what we know.

Then: name the unknown.

Then: write the equation.

Then: solve it.

Then: answer the question.

Last: check.

Answer

x = 5

Your turn

Try this one yourself, then check:

Show the answer

8 hours