Martha needs 7 strawberries for every 1 smoothie.
What are the missing values in the table

Strawberries         Smoothies

28                           4

21                          3

70                      10

Step-by-step explaination

If Maria uses 28 strawberries you would divide that by 7 (since that's how many she uses for one smoothie) after you divide 28 by 7 you get 4, 4 is the number of smoothies 28 strawberries makes.

If Maria makes 3 smoothies you multiple 3 by 7 (since that's how many strawberries she uses to make one) 7 times 3 is 21. If you want to check your work you would divide 21 by 7 (the number of strawberries used for 1 smoothie) and you would get 3.

If Maria uses 70 strawberries you would divide 70 by 7 (the number of strawberries used for 1 smoothie) 70 divided by 7 is 10, 10 is the number of smoothies 70 strawberries make.