\(\left(x-1\right):\frac{1}{2}=\frac{1}{2}+1\frac{1}{2}\)

\(\left(x-1\right).2=\frac{1}{2}+\frac{3}{2}=\frac{4}{2}=2\)

\(x-1=2:2=1\)

\(x=1+1=2\)

27 x 3 + 36 : 4 : 3 x 5 - 25 : 5 x 4

= 81 + 36: 4 : 3 x 5 - 5 x 4

= 81 + 9 : 3 - 20

= 81 + 3 - 20

= 84 - 20

= 64

27 x 56 = 1512

xin lỗi mk chưa học lớp 7