Let the usual speed be \( x \) km/h.
We form the equation: \(\frac{300}{x} - \frac{300}{x+5} = 2\).
Solving, we get \( x^2 + 5x - 750 = 0 \), so roots are 25 and –30.
We reject –30 because speed cannot be negative — in maths and in life, beta, we move forward, not backward.
My grandson explained this to me while I worried over rising train fare costs, and it reminded me how sensible maths is, just like stretching a small pension — only positive numbers work.
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