Let width of rectangle be "x"
L= 3x W=x
if width is diminished by 1 that means new width = (x-1)
similarly the new length would be (3x+3)
hence (x-1)*(3x+3)=72
(3x^2)-3=72
3x^2=75
x^2=25
x= +/- 5
reject -5 as you cant have negative length
hence x=5
so original dimensions of rectangle is
L= 15m W=5m
For the pet the fraction is 2/3 because there is a fish,cat and a dog only cats and dogs have 4 legs and the fraction for the toy or the book is 1/2 because there are 2 objects and she can only get 1