1/3 cup of flour is used to make 5 dinner rolls.
a. how many flour is needed to make one dinner roll?
b. how many rolls can be made with 5 2/3 cups of flour?

Divide.

1/3 / 5

Or multiply by the reciprocal of 5:

1/3 * 1/5 = 1/15

Therefore 1/15 cup of flour is used to make 1 dinner roll.

We can set up a proportion:

5/1/3 = x/5 2/3

Multiply 5 2/3 to both sides:

28 1/3 / 1/3 = x

85 = x

So 85 rolls can be made with 5 2/3 cups of flour.

So 1/3 cup is for 5 so
how much flower per dinner rol
1/3 divided by 5=(1/3)/5=1/3 times 1/5=1/15

1/15 cups used to make 1 dinner roll

with 5 and 2/3 cup
find how many 1/15 will fit
15/15=1 so 15 times 5=75
then 2/3 times 1 or 5/5=10/15 so
75+10=85 dinner rolls