If it takes 4 ounces of insecticide to make 2/1/2 gallons or garden spray, how much spray can be made with 6 ounces of insecticide?

4 oz/2.5 gal garden spray = 6/x
4x = 15
x = 15/4 or 3.75

What you are learning about is Proportions

Ounces               Gallons

4                          2 1/2  or 2.5

6                            x

Don't worry, x just means a number we do not know.

Cross multiply.

4x= 15

    4

4x/4 = x

15/4= 3.75 or 3 1/4

X=3.75 or 3 1/4

Conclusion:
For 6 ounces, it takes 3 1/4 of gallon.

Hope this helps :)