9a)
4x - 2 + 30 = 68
4x + 28 = 68
4x = 40
x = 10
9b)
y = 180 -68
y= 112
x = the length of one piece
y = the length of the other piece
the total length is 100 cm this means
x + y = 100
one piece is 16 inches longer than the other
first we need to convert inches to cm:
1 in = 2.54 cm
16 in = 2.54*16 = 40.64
now we can write
x = y + 40.64
by solving the system of equations
x + y = 100
x = y + 40.64
we find
x = 70.32 cm
y = 29.68 cm
the lengths of the two pieces are 70.32 cm and 29.68 cm.
The 2nd one is the right one.!
The entry in row 1, column 1 of 
is
(i.e. the dot product of row 1 of 
and column 1 of 
)
The entry in row 1, column 2 of is
The second option is the correct answer.
