1
00:00:00,000 --> 00:00:02,708
A box holds N pencils.

2
00:00:04,800 --> 00:00:08,972
Buy three boxes. three N.

3
00:00:11,066 --> 00:00:13,438
When N is twelve.

4
00:00:17,666 --> 00:00:20,134
Tom is X years old.

5
00:00:22,233 --> 00:00:27,869
Mom is twenty-five years older. X plus twenty-five.

6
00:00:29,966 --> 00:00:32,194
When X is ten.

7
00:00:36,283 --> 00:00:39,087
An apple costs Y dollars.

8
00:00:41,183 --> 00:00:45,331
Buy five apples. five Y.

9
00:00:47,416 --> 00:00:49,548
When Y is two.

10
00:00:53,633 --> 00:00:55,573
A rectangle.

11
00:00:57,666 --> 00:01:00,566
When A is four and B is three.

12
00:01:04,666 --> 00:01:07,254
The price is P dollars.

13
00:01:09,350 --> 00:01:14,362
Twenty percent off. 0.8 P.

14
00:01:16,450 --> 00:01:18,678
When P is ten.