Answer is: (a) 64 degrees
Sum of temperatures on 1st, 2nd, 3rd and 4th days
= (58 × 4) = 232 degrees … (1)
Sum of temperatures on 2nd, 3rd, 4th and 5th days
= (60 × 4) = 240 degrees …(2)
Subtracting eqn. (1) from eqn. (2), we get
Temp. on 5th day – Temp. on 1st = 8 degrees
Given, Temp. on 1st day : Temp. on 5th day = 7 :8
∴ 8x – 7x = 8 ⇒ x = 8
∴ Temperature on 5th day = 64 degrees