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Problem 103

Algebra Difficulty 1.2 Multiple choice CEMC Pascal · Canada · 2026

A train consists of one engine and $n$ freight cars. The engine’s length is
$20$ m. Each freight car has length
$15$ m. If the combined length of the
engine and the freight cars is $140$
m, then $n$ equals

Pick one

Official solution

The combined length of the engine and the $n$ freight cars is $140 \text{ m}$ . The length of the engine
is $20 \text{ m}$ , and so the length
of the $n$ freight cars is $140\text{ m}-20\text{ m}=120 \text{ m}$ .
Each freight car has length $15 $\text{}$
m} $, and so$ $n=\dfrac{120\text{ m}}{15\text{}}$ m}}= 8$.

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