Aradio station is giving away tickets to a play. they plan to
give away tickets for seats that cost $10 and $20. they want to
give away at least 20 tickets. the total cost of all the tickets
they give away can be no more than $280.

Step-by-step explanation:

Let x be the number of $10 tickets the radio station gives away and y is the number of $20 tickets which the radio station gives away.

Number of tickets:

At least 20, so

Cost:

x tickets for $10 each cost $10x

y tickets for $20 each cost $20y

Total cost:

$(10x+20y)

The total cost of all the tickets they give away can be no more than $280, so

We get the system of two inequalities: