1996年时，父母的年龄之和是78岁，兄弟二人的年龄之和是17岁；4年后，父亲年龄是弟弟年龄的4倍，母亲年龄是哥哥年龄的3倍，试问：当父亲年龄是哥哥年龄的3倍时是公元多少年？
直接写得数．== 1÷40%=== 72×25%==
直接写出下列题目的得数． 7+66.3=÷=×÷= 14÷=÷20%=（+）×20=
口算．============
直接写得数×12= 0.45×2= 34×0.2=÷2= 10×= 9.9+2.43+0.1=×= 6.8×2.5=
直接写出得数．×= 40%+50%= 81÷= 9.9÷0.1= 3.52+6.48= 1%÷=×2÷×2=
=
= 1÷40%=
=
= 72×25%=
=
÷
=
×
÷
=
=
÷20%=（
+
）×20=
=
=
=
=
=
=
=
=
=
=
=
=
×12= 0.45×2= 34×0.2=
÷2=
= 9.9+2.43+0.1=
×
= 6.8×2.5=
×
= 40%+50%= 81÷
= 9.9÷0.1=
=
×2÷
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