If x and r are directly proportional and x=5 when r= 25, then what is x when r = 40?
Directly proprtional means x = k r where 'k' is the proprtionality constant.
when x = 5 5 = k(25) shows 'k' to = 1/5
when r = 40
x = 1/5 (40) = 8
+67 
