1а) 2(3/4)+4(1/5)=2(15/20)+4(4/20)=6(19/20)
1б) 3(1/6)-1(3/4)=3(2/12)-1(9/12)=1(5/12)
1в) 7(8/15)+1(1/12)-2(11/20)=7(32/60)+1(5/60)-2(33/60)=6(4/60)=6(1/15)
1г) 1(5/12)+7(5/6)+0,75=1(5/12)+7(10/12)+1/4=9(3/12)+3/12=9(6/12)=9(1/2)
<span>1-(1-0,92)*(1-0,9)*(1-0,85)(1-0,8)=0,99976</span>
2+2=4
3+3=6
126+563=689
146899+24689=171588