a; 2/3 × 5/4 - 3/4 × 2/3

= 10/12 - 6/12

= 4/12 =1/3

b; 2 × (-3/2)"^"2 - 7/2

= 2 × 9/4 - 7/2

= 9/2 - 7/2

= 2/2 = 1

c; -3/4 × 5 3/13 - 0,75 × 36/13

= -3/4 × 68/13 - 3/4 × 36/13

= -3/4 × -68/13 - 3/4 - 36/13

= 3/4 × (-68/13 - 36/13)

= 3/4 × (-8)

= -6

 𝕾ố 𝖐𝖍ó𝖒 𝖍𝖔𝖆 đượ𝖈 𝖙𝖗ồ𝖓𝖌 𝖉ọ𝖈 𝖙𝖍𝖊𝖔  𝖈𝖍𝖎ề𝖚 𝖉à𝖎 𝖑à:5,5 ÷ 0,25 +1=23(𝕶𝖍ó𝖒 𝖍𝖔𝖆)

𝕾ố 𝖐𝖍ó𝖒 đượ𝖈 𝖙𝖗ồ𝖓𝖌 𝖉ọ𝖈 𝖙𝖍𝖊𝖔 𝖈𝖍𝖎ề𝖚 𝖗ộ𝖓𝖌 𝖑à: 3,75 ÷ 0,25 +1=16(𝖐𝖍ó𝖒 𝖍𝖔𝖆 )

𝕾ố 𝖐𝖍ó𝖒 𝖍𝖔𝖆 𝖈ầ𝖓 𝖙𝖗ồ𝖓𝖌 𝖑à : (23+16) × 2 - 4=74(𝖐𝖍ó𝖒 𝖍𝖔𝖆) 

𝖁ậ𝖞 𝖘ố 𝖐𝖍ó𝖒 𝖍𝖔𝖆 𝖈ầ𝖓 𝖙𝖗ồ𝖓𝖌 𝖑à 74(𝖐𝖍ó𝖒 𝖍𝖔𝖆)

𝖆,1/5 + 4/5 : x = 0,75

\(\Rightarrow\) 1/5 + 4/5 : x = 3/4

\(\Rightarrow\)      4/5 : x     = 3/4 -1/5

\(\Rightarrow\)      4/5 : x     = 11/20

\(\Rightarrow\)      x             = 11/20 : 4/5

\(\Rightarrow\)    x              = 16/11

𝖇,x + 1/2 = 1-x

\(\Rightarrow\)2x=1 - 1/2

\(\Rightarrow\)2x=1/2

\(\Rightarrow\)x=1/4