I don’t understand question 49 someone pls explain.

Answer:
Below in bold.
Step-by-step explanation:
a, That would be
m = 7 + 8(d - 1) where m = the no. of minutes and d = the day number.
b. On day 9 the number of minutes m = 7 + 8(9 - 1)
= 7 + 64
= 71.