Let the first day be x, then it is X+ 1, X+2,. . X+6
X+X+ 1+X+2+X+3+X+4+X+5+X+6 = 84
X=9
That is, the first day was the 9th and the last day was: 15, so Xiaoming went home on 16.
2. Some cards are marked with 6 12, 18, 24 ... respectively. The number on the last card is 6 larger than the number on the previous card. The nickname got three adjacent cards, and the sum of the numbers on these cards is 342.
(1) What three cards did Xiao Ming get?
(2) Can you get three adjacent cards so that the sum of the numbers on these cards is 86?
Let the first picture be X, then the second picture is X+6 and the third picture is X+ 12.
X+X+6+X+ 12=342
X= 108
Namely: 108, 1 14, 120.
(2)X+X+6+X+ 12=86
X=68/3
Because the numbers on the card are integers, you can't get the sum of 86.