Answer 1a:

(5*4)^(4*5)-56
## [1] 1.048576e+26

Answer 1b:

23-1*(8-12)
## [1] 27

Answer 1c:

56/8*(3+4)
## [1] 49

Answer 1d:

45-5*8+(8+9)
## [1] 22

Answer 2a:

a <- c(2,5,6,7)
a
## [1] 2 5 6 7

Answer 2b:

b <- c(1,0,9,8)
b
## [1] 1 0 9 8

Answer 2c:

c <- c(6,5,8,3)
c
## [1] 6 5 8 3

Matrix:

Attendance <- rbind(a,b,c)

Attendance
##   [,1] [,2] [,3] [,4]
## a    2    5    6    7
## b    1    0    9    8
## c    6    5    8    3
colnames(Attendance) <- c("Mon", "Tue", "Wed", "Thu")

rownames(Attendance) <- c("Present", "Absent", "On leave")

Attendance
##          Mon Tue Wed Thu
## Present    2   5   6   7
## Absent     1   0   9   8
## On leave   6   5   8   3
Sum_of_rows <- rowSums(Attendance)

Sum_of_rows
##  Present   Absent On leave 
##       20       18       22
Sum_of_columns <- colSums(Attendance)

Sum_of_columns
## Mon Tue Wed Thu 
##   9  10  23  18