Answer:
216 cookies
Step-by-step explanation:
From the question,
Let the total cookies in the first place be x cookies.
Their ratio = 5:12:9
Total = 5+12+9 = 26.
Weiming share = (5/26)x = 5x/26
If weiming sold 28 cookies
⇒ (5x/26)-28
⇒ (5x-728)/28
Hence Weiming new share = (5x-728)/28 cookies
The new ratio is 1:8:6
The total cookies becomes = x-28
Therefore,
(1/15)(x-28) = (5x-728)/28
(x-28)/15 = (5x-728)/28
Crossmultiply
28(x-28) = 15(5x-728)
28x-784 = 75x-10920
Collect like terms
28x-75x = -10920+784
-47x = -10136
x = -10136/-47
x = 215.7
x ≈ 216 cookies
