14)(4^{2}+2) x 3 = 54
put the paranthesis around 4 squared and 2
15)a natural number is always a whole number, however, a whole number is not always a natural
16) 10, because natural numbers can only be positive, also, zero is not a natural number
17) 3, for abc/abc will equal 1, leaving 3 x 1 = 3
18) No, for if it is division or multiplication, it will have completely different results
19) (x times y) times z ; x times (y times z) ; x times y times z
hope this helps :D