Well, we know the amount of cups of sugar it calls per 1/2 teaspoon, so all we need to do to find the amount of cups of sugar per teaspoon is multiply by 2, since 1/2 teaspoon * 2 = 1 teaspoon.
2/3 * 2 = 1 1/3
The unit rate is 1 1/3 cups per teaspoon Hope that helped =)
Per teaspoon means per 1 teaspoon we know that the ratio is 2/3:1/2 we want to know x:1 so make them equal since they are in same ratio and fractionify ok so easy peasy (2/3)/(1/2)=x 2/3 times 2/1=x 4/3=x 4/3 cup
or you could recognize that 1/2 times 2=1 so therefor 2/3 times 2=x=