In order to solve this problem,
Create Proportional Relationship.
Let x be number of pounds of orange you could buy when you have $12.
5/3= 12/x
Cross Multiply.
12×3= 36
5×x= 5x
Turn it into a Equation.
5x= 36
Isolate the Variable.
5x÷5= 36÷5
x=7.2
7.2 Pounds of Oranges is the answer
Hope it helps.