Question 163462
Let x=number of raisins that Derek started with

Molly got x/2 raisins and he ate one which equals (x/2)+1

He now has x-((x/2)+1) remaining and this equals:
x-(x/2)-1=((x/2)-1)----remaining

Tricia got (1/2)((x/2)-1)=(x/4)-1/2 and he ate one which equals (x/4)-(1/2)+1=
(x/4)+1/2

He now has remaining:
(x/2)-1-((x/4+1/2)=
(x/2)-1-(x/4)-1/2=
(x/4)-3/2

Clark got (1/2)((x/4)-3/2)=(x/8)-3/4

He now has remaiining
(x/4)-3/2-((x/8)-3/4)=
(x/8)-3/2 + 3/4=(x/8)-3/4 and this we are told equals 7
So:
(x/8)-3/4=7  multiply each term by 8
x-6=56  subtract 6 from each side
x-6+6=56-6 collect like terms
x=50-----------------------number of raisins that Derek started with

CK:
Molly got 50/2=25 and he ate one=24
so he had 26 left
Tricia got 26/2=13 and he ate one =12
So he had 14 left

Clark got 14/2=7
and there's 7 left


Hope this helps---ptaylor