Question

Me ayudan porfavor se lo agradecería ...

Answer 1

Manda las mejor por inbox

Answer 2

42.
[(-1/4) + (-1/5)] - (-1/7) + (1/4) - {-[-(1/2 + 4/7)]} =
[-1/4 -1/5] + 1/7 + 1/4 - {-[-(7+8/14)]} =
[-5-4/20] + 1/7 + 1/4 - {-[-15/14]} =
-9/20 + 1/7 + 1/4 - {+15/14} =
-9/20 + 1/7 + 1/4 - 15/14 = 
-63+20+35-150/140 = -158/140 = -79/70

43.
1/3 - {-[5/2 - (3/2 - 1/4) - 8/10] - 1/5} -[-(-2/5) + (-1/3)] =
1/3 - {-[5/2 -(6-1/4) - 4/5] - 1/5} - [2/5 - 1/3] =
1/3 - {-[5/2 - 5/4 - 4/5] - 1/5} - [6-5/15] =
1/3 - {-[50-25-16/20] - 1/5} - 1/15 =
1/3 - {-9/20 - 1/5} - 1/15 = 
1/3 - {-9-4/20} - 1/15 =
1/3 - {-13/20} - 1/15 =
1/3 + 13/20 - 1/15 = 20+39-4/60 = 55/60 = 11/12