The temperature of a solid falls from $\;77^{0}C\;$ to $\;73^{0}C\;$ in 3 minutes and $\;73^{0}C\;$ to $\;69^{0}C\;$ in 4 minutes . What is the room temperature ?

Question

$(a)\;59\qquad(b)\;61\qquad(c)\;71\qquad(d)\;91$