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倒推时间 = kira ke belakang 题目知道的是最后的时间（派对开始），问的是最早要开始准备的时间，所以要从结束往回减。先减“提早到”的时间，得到要抵达的时间；再减路程时间，得到出门时间；最后减准备的时间。 例子：7:30 p.m. 开始，提早 10 分钟，路程 30 分钟 → 7:30 − 10 分 − 30 分 = 6:50 p.m.。 注意：往回推要用减法；每一段都不能漏掉。

work backwards = kira ke belakang The question gives the final time (when the party starts) and asks when Hana must begin, so subtract backwards. First subtract the time she wants to be early to get her arrival time, then the travel time to get her leaving time, then the time to get ready. Example: an event at 7:30 p.m., arriving 10 minutes early with a 30-minute journey → 7:30 − 10 min − 30 min = 6:50 p.m. Watch out: working backwards means subtracting, and no part may be left out.

几倍求一倍 = cari satu bahagian “是……的四倍”表示大的年龄要除以四，才得到小的年龄。先把 dekad 和年全部换成年，除以四，再把结果写回 dekad 和年。也可以先除 dekad，余下的 dekad 换成年再除。 例子：7 dekad 5 年是某数的 3 倍 → 75 ÷ 3 = 25 年 = 2 dekad 5 年。 注意：余下的 dekad 不能丢掉；写回时十年才是一个 dekad。

one share from times as much = cari satu bahagian '4 times the age of' means divide the bigger age by 4 to get the smaller one. Change the dekad and years into years, divide by 4, then write the result back in dekad and years. Or divide the dekad first and change the leftover dekad into years. Example: 7 dekad 5 years is 3 times a number → 75 ÷ 3 = 25 years = 2 dekad 5 years. Watch out: do not drop the leftover dekad, and 10 years make one dekad.

两次换算 = tukar dua kali 小时不能直接换成周，要分两步：先用小时除以二十四，换成天；再用天数除以七，商是周，余数是天。 例子：240 小时 → 240 ÷ 24 = 10 天 → 1 周 3 天。 注意：第一步得到的是天数，不要把它直接当成“几周几天”来读。

change twice = tukar dua kali Hours cannot go straight to weeks, so use two steps: divide the hours by 24 to get days, then divide the days by 7; the quotient is weeks and the remainder is days. Example: 240 hours → 240 ÷ 24 = 10 days → 1 week 3 days. Watch out: the first step gives days; do not read that number as weeks and days.