Thu wants to play "guess my number". she states,"when I triple my number and add five, I get twenty-six. What's my number?" what is her number?

Let's break this up:

let x = the number

"when I triple my number" is the same as

3x

"and add five" is the same as

+5

We combine it to get

3x+5

"I get twenty-six"

=26

combine to get

3x+5=26

Now we just solve:

subtract 5 from both sides to get

3x=21

divide by 3 to get

x=7