Answer:
4.11
Explanation:

Multiply both sides by 100:


In order to divide you find how many times 19 can go into 78 and then subtract. So if 19 can go into 78, 4 times then subtract 78 by 76 since 19 times 4 = 76.
You continue dividing and once you are no longer capable of substracting you are given a remainder. (make sure to bring your decimal point straight up when solving)
Dividing 78.09 by 19 will give you 4.11 with no remainder.
I hope this helps.