列式计算.(1)16与3.2的积减去什么数的3 倍等于22.4(2)一个数的4倍加上这个数的1.5倍等于40.7,求这

2024-12-03 10:41:08
推荐回答(2个)
回答1:

(1)设这个数为x,得:
16×3.2-3x=22.4
   51.2-3x=22.4
        3x=28.8
         x=9.6
答:16与3.2的积减去9.6的3 倍等于22.4.

(2)设这个数是x,由题意得:
4x+1.5x=40.7
   5.5x=40.7
      x=7.4;
答:这个数是7.4.

(3)(5.6+0.7)×(1-0.4)
=6.3×0.6
=3.78;
答:积是3.78.

(4)设这个数为x,由题意得:
4x-x=42.6
  3x=42.6
   x=14.2;
答:这个数是14.2.

回答2:

(1)设这个数为x,列方程:16×3.2-3x=22.4
解答:51.2-3x=22.4
-3x=22.4-51.2=-28.8
x=-28.8÷(-3)
=9.6
(2)设这个数为x,列方程:4x+1.5x=40.7

解答:5.5x=40.7
x=40.7÷5.5
=7.4
(3)(5.6+0.7)×(1-0.4)
=6.3×0.6
=3.78
(4)设这个数为x,列方程:4x-x=42.6
解答:3x=42.6
x=42.6÷3
=14.2