Answer:
Miki had 288 stickers and Ken had 252 stickers.
Step-by-step explanation:
This question is solved using a system of equations.
I am going to say that:
Miki has x stickers.
Ken has y stickers.
The ratio of the number of Miki's stickers to the number of Ken's stickers was 8:7.
This means that
, that is:
, or 
After Miki gave Ken 18 of her stickers, they had the same number of stickers.
This means that:


Since 




And


Miki had 288 stickers and Ken had 252 stickers.