`#Sad`
`a,`
`11(3)/(13)-(2(4)/(7)+5(3)/(13))`
`= (146)/(13)-((18)/7+(68)/(13))`
`= (146)/(13)-(710)/(91)`
`= (24)/7`
`b,`
`4/7+5/6 : 5-0,375 . (-2)^2`
`= 4/7+1/6-0,375 .4`
`= 4/7+1/6-1,5`
`= (-16)/(21)`
`c,`
`1/4+3/4(-1/2+2/3)`
`= 1/4+3/4. 1/6`
`= 1/4+1/8`
`= 3/8`