add-or-subtract

基本解释

Add or subtract a daily meal, and you soon gain or lose a surge.
一天加入/减少一餐，不久，人们就会失去/得到一次要吃的冲动。
If born before 1930 of after 1993,add or subtract 12 to find your year.
如果早于1930年或者晚于1993年，则加减12得到代表你的年份。
Understand and grasp the simple ways to add or subtract a number which is close to a round number.
理解并掌握一个数加上或减去接近整十、整百的数的简便算法。
Look at the minuend and subtrahend. They both add or subtract the same number. The differences are the same.
小结：被减数减少(或增加)，减数也作相应的减少(或增加)，差不变。
This one had numbered dials that could be turned to add or subtract columns of numbers.
这部机器上标有数字的转盘能转动来加减成串的数字。