1.
a)2/5+3/5 : (-3/2)+1/2
=1.2/-3+1/2
=2/-3+1/2
=4/-6+(-3)/-6
=1/-6
b)10 1/4 :(-3/5)-8 1/4 : (-3/5)
=(5/-3)( 10 1/4 - 8 1/4)
=5/(-3) . 2
=10/-3
c)căn bậc của 25/49+(-2020)^0+l-2/7l
=5/7+1+2/7
=1+1
=2
d)(1+2/3-14/9):(5/6-4/5)^2
=(9+6-14/9):(25-24/30)^2
=1/9 : 1/900
=1/9.900
=100