14. While conducting observations on a geographical site, students recorded the temperature daily from April 15 to April 19 inclusive. The average temperature over these days was $17.5^{\circ}$. What were the temperatures on April 19 and April 15, if the temperature increased by $1.5^{\circ}$ daily?
14. If the temperature increased daily by $1.5^{\circ}$ on the 15th, 16th, 17th, 18th, and 19th, then the average temperature was on the 17th. If the temperature on April 17th was $17.5^{\circ}$, then on April 19th it was $17.5^{\circ}+3^{\circ}=20.5^{\circ}$, and on April 15th it was $17.5^{\circ}-3^{\circ}=14.5^{\circ}$.