（清原县）求未知数 ①：x=0.3： ②1﹣25% x="0.5" ③6x﹣7.3=19.7．
0.8+0.55+1.2-0.45
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1--
口算。+=-=+=-+= 0.63×1000= 0. 75-0.25= 0.07+0.03= 0. 9÷0.03= 0.4×0.8=
×=÷3=÷=－= 3÷15=＋0.25= 1÷= 85%－15%= 10÷10%= 5×÷5×=
：x=0.3：
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÷3=
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÷5×
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