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Algebra Difficulty 1.2 Junior Find the answer Canada

If the symbol
$ $\begin{array}{c|c} p & q \\ \hline r & s \\ \end{array}$ $
is defined by $p \times s - q \times r$ , then the value of $ $\begin{array}{c|c} 4 & 5 \\ \hline 2 & 3 \\ \end{array}$ $ is

Pick one

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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Source: CEMC, University of Waterloo, licensed CC-BY-NC-4.0. Statement reproduced verbatim; metadata (topic, difficulty) added by this project.