Building and solving an equation, it is found that the department store has 12 floors.
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- The number of floors is n.
- Middle floor is [tex]\frac{n}{2}[/tex].
- Goes up three floors, so [tex]\frac{n}{2} + 3[/tex]
- Down five floors, so [tex]\frac{n}{2} + 3 - 5 = \frac{n}{2} - 2[/tex].
- Up six, so [tex]\frac{n}{2} - 2 + 6 = \frac{n}{2} + 4[/tex].
- Down ten, on the first floor, so: [tex]\frac{n}{2} + 4 - 10 = \frac{n}{2} - 6 = 0[/tex]
Solving, we find the number of floors.
[tex]\frac{n}{2} - 6 = 0[/tex]
[tex]\frac{n}{2} = 6[/tex]
[tex]n = 12[/tex]
The store has 12 floors.
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