Because, if 6 + 6 = 12, then in 6 + 7, 7 can be splitted into 6 + 6 + 1, and so you find it easier...!!
The answer is 20.5 try it good luck
Answer:
I'm using algebra format ok so if u get it wrong pls dont kill me. 6(3+4) = 6*3 + 6*4 brackets in algebra means times so 6 times 3 + 6 times 4 done