Yvonne ran up 1/4 of the total flights of staris in an office building and walked up the rest of she walked up 9 flights of stairs, how many flights did she run up?
3
9
12
27
36

Yvonne ran up 12 flights of stairs.

Explanation:
Understand the situation:

Yvonne ran up 1/4 of the total stairs. Afterwards, she walked the REST of the stairs, which is said to be 9 STAIRS. HOW MANY flights of stairs IN TOTAL did she run up?

When she ran the REST of the stairs, it meant she ran the other 3/4 of stairs because:
1 - 1/4 = 3/4

To add someting, that means that the 9 stairs is 3/4 of the total stairs, so lets fins the total stairs using this information:
9 ÷ 3/4 = 12

LETS CHECK IF 9 IS REALLY 3/4 of 12:
12 x 3/4 = 9

HOPE THIS HELPS
-SpaceMarsh

Sorry can u repeat that?