3. The boy thought of a number. He added 5 to that number, then divided the sum by 2, multiplied the quotient by 9, subtracted 6 from the product, divided the difference by 7, and got the number 3. What number did the boy think of?
3. We calculate backwards:
$3 \cdot 7=21$
1 POINT
$21+6=27$ 1 POINT
$27: 9=3$ 1 POINT
$3 \cdot 2=6$ 1 POINT
$6-5=1$
1 POINT
The desired number is 1.
1 POINT

(Note: If the student has written that the solution is the number 1 and has only verified the correctness of this solution, they should receive 2 POINTS.)