In a shop where it sells televisions, all of them with a price of 1596\$, they managed to sell 42 televisions. After an increase of price of those televisions, they sold 38 televisions and earned 1140\$. Find the increase of the price of the televisions.
This is a quite easy and simple problem, but we get different answers:
$\\ \mathbf{My\ method:}$ I simply found the $\frac{\$}{televisions}$ of each time, for the time before the increase: $$\frac{1569}{42}=380\$/television$$ and after the increase $$\frac{1140}{38}=30\$/television$$ so the final answer I thought it was $$380\$/television-30\$/television=350\$/television$$ they increased $350\$ $ per television. Is there anything wrong with this method? If so, what is it?