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求未知数x.(1)40-x=4.01(2)x+8.07=13.047(3)x×78=84240(4)x÷1.3=325.

题目详情
求未知数x.
(1)40-x=4.01           
(2)x+8.07=13.047
(3)x×78=84240           
(4)x÷1.3=325.
▼优质解答
答案和解析
(1)40-x=4.01
      40-x+x=4.01+x
          40=4.01+x
     40-4.01=4.01+x-4.01
           x=35.99;

(2)x+8.07=13.047
x+8.07-8.07=13.047-8.07
          x=4.977;

(3)x×78=84240
 x×78÷78=84240÷78
         x=1080;

(4)x÷1.3=325
x÷1.3×1.3=325×1.3
          x=422.5.