\(a)2^3\cdot15-[115-(12-5)^2]\\=8\cdot15-(115-7^2)\\=120-(115-49)\\=120-66\\=54\\---\\b)5\cdot[(85-35:7):8+90]-60\\=5\cdot[(85-5):8+90]-60\\=5\cdot(80:8+90)-60\\=5\cdot(10+90)-60\\=5\cdot100-60\\=500-60\\=440\)
\(---\)
\(c,\left\{\left[261-\left(36-31\right)^3\cdot2\right]-9\right\}\cdot1001\)
\(=\left[\left(261-5^3\cdot2\right)-9\right]\cdot1001\)
\(=\left[\left(261-125\cdot2\right)-9\right]\cdot1001\)
\(=\left[\left(261-250\right)-9\right]\cdot1001\)
\(=\left(11-9\right)\cdot1001\)
\(=2\cdot1001\)
\(=2002\)
\(---\)
\(d,3\cdot10^2-\left[1200-\left(4^2-2\cdot3\right)^3\right]\)
\(=3\cdot100-\left[1200-\left(16-6\right)^3\right]\)
\(=300-\left(1200-10^3\right)\)
\(=300-\left(1200-1000\right)\)
\(=300-200\)
\(=100\)
#\(Toru\)
a) 23.15 -[115-(12-5)2 ]
= 23.15 -[115-36]
= 8.15 -79
= 120-79
=41
b)5.[(85 - 35 : 7) :8 + 90 ] - 50
=5 .[80:8+90]-50
=5.100-50
=500-50
=450
c){[261 - ( 36-31)3.2 ]-9}.1001
={[261 - 125.2 ]-9}.1001
={[261 -250 ]-9}.1001
={11-9}.1001
=2.1001
=2002
d)3.102 - [1200 - ( 42 - 2.3)3]
=3.100-[1200 -(16-6)3 ]
=300-[1200-1000]
=300-200
=100
