А)5/9*3/20=1/3*1/4=1/12;
б)15*16/26=48/5=9 3/5;
в)1ц1/2=3/2*3=9/2=4ц 1/2;
г)7/12*8/21=1/3*2/3=2/9;
д)18*2/9=2/1*2/1=4/1=4;
е)1ц1/4*5=5/4*5=25/4=6ц 1/4.
1) (148+а)-96=(148-96)+а=52+а
2) (205+b)-183= (205-183)+b=22+b
3) (с+75)-38=с+(75-38)=с+37
<span>(d+83)-54=d+(83-54)=d+29</span>
720:(90-х)+45=125
720:(90-х)=125-45
90-х=720:80
90-х=9
х=90-9
х=81