1.6 (2x - 0.42) = 2 4/5 * 7/20
1.6 * 2x + 1.6 * (-0.42) = 2.8 * 0.35
3.2x - 0.672 = 0.98
3.2x = 0.980 +0.672
3.2x= 1.652
x= 1.652 : 3.2 = 1652/3200 = 413/800
x = 0.51625
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1.6 * ( 2 * 0.51625 - 0.42) = 2 4/5 * 7/20
1.6 * ( 1.0325 - 0.4200 ) = 14/5 * 7/20
1.6 * 0.6125 = 98/100
0.98 = 0.98