5t = 15.55. Here's why:
Since in the equation 9t = 27.99 is basically multiply two numbers to get a product, divide 27.99 by 9:
27.99/9 = 3.11
3.11 is the value of t. So now that we've found the value of t, plug it into the equation 5t like so:
5*3.11 = 15.55
I hope this helped you out! :)