Question

Inequality (please check the attached image)​

Answer 1

Let the number of pens be p and number of pencil cases be c.

• Each pen costs php 20 and all pens cost 20p.
• Each pencil case costs php 40 and all pencil cases cost 40c.
• Total amount Dona needs to make is at least 2000.

Use given information and set inequality:

• 20p + 40c ≥ 2000

Simplify it by dividing all terms by 20:

• p + 2c ≥ 100

If number of pens is more than 100, we get:

• p > 100

Substitute this into inequality:

• 100 + 2c ≥ 100 Subtract 100 from both sides
• 2c ≥ 0 Divide both sides by 2
• c ≥ 0

If Dona sells more than 100 pens then she will exceed php 2000 regardless the number of pencil cases sold.