Lidia bought a new tablet, and she needs to buy some apps for it. One app costs $4 on average, and Lidia needs 15 of them. She has $66 for this purpose. How much money will she be left with if she buys all the apps she needs?
So Lidia will spend 4 * 15 = $<<4*15=60>>60 on apps.
She already has $66, so she will be left with 66 - 60 = $<<66-60=6>>6.
#### 6