The floor

The floor collapsed because three and a half times the amount it had been designed to hold had been stored in the room. If we had stored 980 tons in the room, what amount was the floor designed to hold?

Correct answer:

m =  280 t

Step-by-step explanation:

$$\begin{gathered} M=980\text{t} \\ k=3\frac{1}{2}=3+\frac{1}{2}=\frac{3\cdot 2+1}{2}=\frac{6+1}{2}=\frac{7}{2}=3.5 \\ m=M/k=980/\frac{7}{2}=980:\frac{7}{2}=980\cdot \frac{2}{7}=\frac{980\cdot 2}{7}=\frac{1960}{7}=280\text{t} \end{gathered}$$

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