(15 - 13 4/97) * ( 1 4/5 + 7/50) / (12 7/10 - 7) = 2/3
1) 15 - 13 4/97 = 14 97/97 - 13 4/97 = 1 93/97
2) 1 4/5 + 7/50 = 1 40/50 + 7/50 = 1 47/50
3) 12 7/10 - 7 = 5 7/10
4) 1 93/97 * 1 47/50 = 190/97 * 97/50 = 190 / 50 = 19/5
5) 19/5 : 5 7/10 = 19/5 : 57/10 = 19/5 * 10/57 = 2/3
Х : 40=380+580
х:40= 960
х= 960 * 40
х= 38400
960=960
Х - неизвестное число,
2/7х+0,8=1,2
2/7х=1,2-0,8
2/7х=0,4
2/7х=2/5
Х=2/5:2/7
Х=(2*7) / (5*2)=7/5=1 2/5=1,4
Х=1,4