The price of a product has increased by 40%. By what percentage do we need to reduce our consumption of this product if we can only spend 12% more money on its purchase?
Originally, the unit price of the product was $X$ Ft, and we spent $Y$ Ft on it, which allowed us to buy $\frac{Y}{X}$ units of the product.

If the unit price increases by $40 \%$, making it $1.4 X$ Ft, and our capital increases by $12 \%$, making it $1.12 Y$ Ft, then we can buy $\frac{1.12 Y}{1.4 X}$ units of the product. This is the percentage of the originally purchasable quantity:

$$
\frac{1.12 Y}{1.4 X}:\left(\frac{Y}{X} \cdot \frac{1}{100}\right)=\frac{112}{1.4}=80
$$

percent, which means our consumption decreases by $20 \%$.