Because, if 6 + 6 = 12, then in 6 + 7, 7 can be splitted into 6 + 6 + 1, and so you find it easier...!!
So, I'm assuming that the x represents multiplication...
Because multiplication has a higher precedence over addition, we'll multiply the numbers first:
18 + 48
Then we simply add:
66
I think the answer is either 3/49 or about 0.061
hope this helps.
