Question 757288
This is a similar triangle question.
You have to use the ratio of the two similar sides
The tree/ Ronnie = The tree's shadow/ Ronnie's shadow
 24/6 = 12/x
Cross multiply
24x = 72
Divide both sides by 24
 x = 3
Therefore Ronnie's shadow will be 3 feet long.
Hope this helps.
:-)