First, let's define a variable:
x: number of times you can buy lunch per week.
We write the following inequality:
2x <= 10
Clearing x we have:
x <= 10/2
x <= 5
Answer:
An inequality to finding the maximum number of times per week Johanna can buy her lunch is:
2x <= 10
solve an inequality:
x <= 5
(You can buy a maximum of 5 lunches per week).