4 tickets cost $28 and 6 tickets cost $42. Is the cost proportional…

Step by step

The question

Question: 4 tickets cost $28, and 6 cost $42: is the cost proportional to the number of tickets?

Let x be the number of tickets.

Let y be the cost.

Proportional means: y divided by x is always the same number.

We call that number k.

Then y = k times x.

1 Divide y by x

For each pair we work out y divided by x.

28/4 is 7.

42/6 is 7.

2 Compare the answers

The same number every time.

So it is proportional, and k = 7.

3 Write the equation

y = k x, with k = 7.

So the equation is y = 7x.

4 Check

Let's check: k times x should give each y.

7 times 4 is 28.

7 times 6 is 42.

So the answer is right!

Let's look back.

First: divide y by x.

Then: compare the answers.

Then: write the equation.

Last: check.