#1
a) (-2/7)'2=4/49
б) 3'4-5'0=81-1=80
#2
a)x'5*x'6*x'8=x'19
b)x'16:x'7:x'8=x
#3
5'7*6'7:30'5=30'7:30'5=30'2=900
3'3*3'9:3'8=3'12:3'8=3'4=81
900+81=981
#4
(x'2)'7*(x'3)'9:x'30/x*x'9=-3111
x'14*x'27:x'30/x'10=-3111
x'11/x'10=-3111
x=-3111
#5
(-3)'4 (2,4)'4 (-1,5)'2 (-9)'0 (-2)'3 (-7)'5