Final answer:
The number in question is 6, as it is greater than 3, less than 9, and it is the total number of sides in two triangles (3 sides per triangle times 2).
Step-by-step explanation:
The student has asked for help with finding a one-digit number that is greater than 3 but less than 9 and equals the number of sides in two triangles. Knowing that each triangle has three sides, we can calculate the total number of sides in 2 triangles by multiplying 3 by 2, which is 6. This satisfies both conditions: it's more than 3, less than 9, and represents the number of sides in two triangles.