已知8x-2.5×8=24.8,那么0.38+1.2x=_ 已知6x÷4.5=8,那么7x-_=29.5.

问题描述:

已知8x-2.5×8=24.8,那么0.38+1.2x=______
已知6x÷4.5=8,那么7x-______=29.5.

(1)8x-2.5×8=24.8
            8x-20=24.8
         8x-20+20=24.8+20
               8x=44.8
            8x÷8=44.8÷8       
                x=5.6;
0.38+1.2×5.6
=0.38+6.72
=7.1;
(2)6x÷4.5=8
6x÷4.5×4.5=8×4.5
          6x=36
       6x÷6=36÷6
           x=6;
7×6-29.5
=42-29.5
=12.5.
故答案为:7.1、12.5.