4 is the X variable so it means it is 4 weeks after the kitten is born.
14 is the Y variable so it means it is 14 ounces after 4 (this is the X variable) weeks.
Multply across the fraction so
1/2 * 3/4= (1*3)/(2*4)=3\8
when you simplify this you get 1/16x^8
The problem statement gives you the relationship between their speeds, and it gives you information you can use to find their total speed. You solve this by finding the total speed, then the proportion of that belonging to Bill.
The total speed is (120 mi)/(3 h) = 40 mi/h.
The speed ratio is ...
... Bill : Joe = 3 : 1
so the speed ratio Bill : Total is ...
... 3 : (3+1) = 3:4.
Bill's speed is (3/4)×(40 mi/h) = 30 mi/h.