Competition problem — Algebra — Maths Olympiad Prep

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Algebra Difficulty 1.3 Junior Find the answer

Numbers $m$ and $n$ are on the number line. What is the value of $n-m$ ?

Your answer

A number or a short expression. Fractions can be typed as 3/2, and spacing doesn't matter.

Solution

On a number line, the markings are evenly spaced. Since there are 6 spaces between 0 and 30, each space represents a change of $\frac{30}{6}=5$ . Since $n$ is 2 spaces to the right of 60, then $n=60+2 \times 5=70$ . Since $m$ is 3 spaces to the left of 30, then $m=30-3 \times 5=15$ . Therefore, $n-m=70-15=55$ .

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