If the sandbar shark is 4 1/2 feet long and the thresher shark is 3 times as long then the equation would look like this:
3s=T or 4 1/2 • 3 = T.
Now you would multiply the 4 1/2 and the 3. You could keep it in fraction form or you could convert it to decimal form.
Fraction:
You need to convert the 4 1/2 into an improper fraction. You can do this by multiplying the 4 by the 2 and adding 1. Aka 9/2. You also need to make the 3 into a fraction, this is easy, all you have to do is add a 1 as the denominator.
9/2 • 3/1
Multiply the 9 and 3 and then the 2 and 1. This should leave you with 27/2. Now convert this into a proper fraction.
27 / 2 = 13.5
The thrasher shark is 13.5 ft
Decimal:
4 1/2 is 4.5 in decimal form. Multiply 4.5 by 3.
4.5 • 3 = 13.5
The thrasher shark is 13.5 ft
Both ways get you the same answer, use whichever way makes the most sense to you.