Maths Olympiad Prep

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Algebra Difficulty 1.5 Junior Find the answer Canada

If $2mnn=35\$\dfrac{2m-n}{n} = \dfrac{3}{5},thenthevalueof, then the value of mn$\dfrac{m}{n}\$ is

Pick one

Solution

Solution 1:

If 2mnn=35\dfrac{2m-n}{n}=\dfrac35,
then 5(2mn)=3n5(2m-n)=3n or 10m5n=3n10m-5n=3n. Simplifying, we get 10m=8n10m=8n and so mn=810=45\dfrac{m}{n}=\dfrac{8}{10}=\dfrac45.

Solution 2:

If 2mnn=35\dfrac{2m-n}{n}=\dfrac35,
then 2mnnn=35\dfrac{2m}{n}-\dfrac{n}{n}=\dfrac35 or
2mn1=35\dfrac{2m}{n}-1=\dfrac35.
Simplifying, we get 2mn=85\dfrac{2m}{n}=\dfrac{8}{5}, and so mn=85×12=45\dfrac{m}{n}=\dfrac{8}{5}\times\dfrac12=\dfrac45.

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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.