bài 1: tính a) (3/5 + 7/5) : 1/-4 b)3/7 + -4/7 . 1/4 c) (/12 + -5/9) mũ 2 : 36 d) 4/3 : 7/5 – 2/3 : 7/5

bài 1: tính
a) (3/5 + 7/5) : 1/-4
b)3/7 + -4/7 . 1/4
c) (/12 + -5/9) mũ 2 : 36
d) 4/3 : 7/5 – 2/3 : 7/5