Final answer:
To find out how many text messages Tiffany's brother sent, we use the ratio of messages sent by Tiffany to her brother (3:4). Tiffany sent 12 messages; therefore, her brother sent 16 messages after setting up a proportion and solving for the unknown number.
Step-by-step explanation:
The number of text messages sent by Tiffany compared to her brother is in the ratio of 3:4. Tiffany sent 12 text messages. To find out how many messages Tiffany's brother sent, we can set up a proportion where 3 corresponds to Tiffany's 12 messages, and 4 will correspond to her brother's number of messages, which we can call x. The proportion is:
3/4 = 12/x
By cross-multiplying to solve for x, we get:
3x = 4 × 12
3x = 48
x = 48/3
x = 16
So, Tiffany's brother sent 16 text messages.