A cup of tea is initially at a temperature of ${85}^{\circ }\text{C}$ and cools in a room maintained at ${20}^{\circ }\text{C}$. If the cooling constant is $k=0.03$ ${\text{min}}^{-1}$, after how many minutes will the tea reach ${40}^{\circ }\text{C}$? Round your answer to the nearest whole number.