19 tens + 11 tens what's the answer

First we can either add 19 and 11, or we can do this another way.

19 + 11 = 30     To find how much thirty tens are, just add a 0 on the end of 30: 300

The other longer way to do it is: add a 0 to 19: 190, then add a 0 to 11: 110

110 + 190 = 300

There is your answer!

C. expression because any expression or equation may contain more than one variable