4. The length and width of a rectangular prism are 20 cm and 15 cm, respectively. If the numerical value of its volume is equal to the numerical value of its surface area, then its height is cm (write the answer as an improper fraction)

The length and width of a rectangular prism are 20 cm and 15 cm, respectively. If the numerical value of its volume is equal to the numerical value of its surface area, then its height is cm (write the answer as an improper fraction)
【Answer】 $\frac{60}{23}$
Analysis: Let the height be $\mathrm{h}$, then $20 \times 15 \times \mathrm{h}=(20 \times 15+20 \mathrm{~h}+15 \mathrm{~h}) \times 2$, so $\mathrm{h}=\frac{60}{23}$