In a month's calendar, the sum of the four days of Thursdays and Fridays in two adjacent lines is 24, so what day is the 1st of this month?

In a month's calendar, the sum of the four days of Thursdays and Fridays in two adjacent lines is 24, so what day is the 1st of this month?

The first line is x on Thursday and X + 1 on Friday
The second line is x + 7 on Thursday and X + 8 on Friday
x+x+1+x+7+x+8=24
X = 2, Thursday is the 2nd, so the 1st is Wednesday

Circle three adjacent dates on the same column of the calendar and calculate their sum, which may be ()
A.90 B.38 C.48 D.6
The score will be given later!
On the first floor! 29 + 30 + 31 =?

Let the middle of the three dates be X
Then (x-1) + X + (x + 1) = 3x
I don't know right or wrong
But it seems that only B is wrong
Because 90, 48, 6 are divisible by 3