i dont understand the question for D can someone please explain it

Answer:
71°
Step-by-step explanation:
The average temperature is calculated as
Average = [tex]\frac{sum}{count}[/tex]
let x be the temperature in October, then
[tex]\frac{25+70+65+85+92+82+x}{7}[/tex] = 70, that is
[tex]\frac{419+x}{7}[/tex] = 70 ( cross- multiply )
419 + x = 490 ( subtract 419 from both sides )
x = 71
Average temperature in October was 71°