Answer:

The ratio of milk to water in the recipe is:

1

3

cup of milk

1

4

cup of water

Letting

x

represent the amount of water when the milk is equal to a cup, the ratio to represent that is:

1

cup of milk

x

cup of water

Equating the ratios to each other and cross multiplying, the amount of water needed is:

1

3

cup of milk

1

4

cup of water

=

1

cup of milk

x

cup of water

(

x

)

(

1

3

)

=

(

1

)

(

1

4

)

(

3

)

(

x

3

)

=

(

3

)

(

1

4

)

x

=

3

4

cup of water

The recipe needs

3

4

cup of water

for 1 cup of milk.