a,
(27+65)+(346-27-65)
=92+254
=346
b,
(42-69+17)-(42+17)
=-10-59
=-69
tick nha
a) (27+65) + (346-27-65)
= 27 + 65 + 346 - 27 - 65
= 27 - 27 + 65 - 65 + 346
= 0 + 0 + 346
= 346
b) (42-69+17) - (42+17)
= 42 - 69 + 17 - 42 - 17
= 42 - 42 + 17 - 17 - 69
= 0 + 0 - 69
= -69