1.
a)2 2/5+3 3/5=12/5+18/5=30/5=6
b) 1/5 * 3/2 =3/10
c) (-2/3)³=-8/27
2.
a=3 a+1/a=3+1/3=(3*3+1)/3=10/3
3.
a=0,(3) = 3/9=1/3
b=2/3
a:b= 1/3 : 2/3 =1/3 * 3/2=1/2
4.
2,75-3+1,25+4,87+3+0,13=
=2,75+1,25+4,87+0,13=
=4+5=9
(1 2/3*5/7) *(3/2*7/5)*3/5=
=(5/3*5/7) *21/10*3/5=
=25/21 *21/10*3/5=
=5/1 *1/2*3/5=
=1/1 *1/2*3/1=
=3/2