a) \(64\left(57+43\right)-2300=64.100-2300=6400-2300=4100\)

\(\Leftrightarrow\left(6,45+3,55\right)\times y=20180\)

\(\Leftrightarrow10\times y=20180\)

\(\Leftrightarrow y=20180:10\)

\(\Leftrightarrow y=2018\)

= y. ( 6,45 + 3,55 ) = 20180

= 10y = 20180

=> y = 2018

dấu chấm (.) là dấu nhân nhé 

\(6,45\cdot y+y\cdot3,55=20180\)

\(y\cdot\left(6,45+3,55\right)=20180\)

\(y\cdot10=20180\)

\(y=20180:10\)

\(y=2018\)

a,  15 . { 32 : [ 6 - 5 + 5 ( 9 : 3 ) ] + 3 } - 2018 0

= 15.{32:[1+15]+3}–1

= 15.5–1

= 74

b,  25 . { 2 7 : [ 12 - 4 + 2 2 . 16 : 2 3 ] - 2 4 }

= 25.{128:[8+4.2]–16}

= 25.24

= 600

c,  2019 . { 101 - 1000 : [ 2 2 . 2 3 + 5 6 : 5 3 - 6 2 : 11 - 2018 0 ] }

= 2019.{101–1000:[(32+125–36):11–1]}

= 2019.{101–1000:[121:11–1]}

= 2019.{101–1000:10}

= 2019.1

= 2019

\(\left(-1\right)^{2018}-250 :\left(-5\right)^2-2018^0\)

\(=1-250:25-1\)

\(=-250:25\)

\(=-10\)

\(2018^0\left\{15^2:\left[175+2^3.5^2\right]\right\}\\ =1\left\{225:\left[175+8.25\right]\right\}\\ =225:\left[175+200\right]\\ =225:375\\ =\dfrac{3}{5}\)

28²⁰¹⁸:7²⁰¹⁸:2018⁰=(28:7)²⁰¹⁸:1=4²⁰¹⁸:1=4²⁰¹⁸

\(=-\dfrac{8}{5}\left|-\dfrac{3}{4}\right|+1=-\dfrac{8}{5}\cdot\dfrac{3}{4}+1=-\dfrac{6}{5}+1=-\dfrac{1}{5}\)