4. 765-!-item-!-187;#058&000550
In a stack of boards at a lumber yard, the 20th board counting from the top of the stack is immediately below the 16th board counting from the bottom of the stack. How many boards are in the stack?
(A) 38
(B) 36
(C) 35
(D) 34
(E) 32
我怎麼算都是35,答案是D
可能是我數學不太好,請各位高手指點一下,謝謝