( -7.2, -98.6, 0.0 )T - ( -2.2, -2.4, 3.0 )T = 
( -7.2 -(-2.2), -98.6 -(-2.4), 0.0 - 3.0)T = 
( -5.0, -96.2,  - 3.0)T 

Moving "-" Inside

You may find the following an easier way to do the problem:

( -7.2, -98.6, 0.0 )T - ( -2.2, -2.4,  3.0 )T = 
( -7.2, -98.6, 0.0 )T + ( +2.2, +2.4, -3.0 )T = 
( -5.0, -96.2, - 3.0)T 

The "outside -" was used to negate the second matrix, then the resulting two matrices were added. In symbols:

a - b = a + (-b)

This can be more useful to remember than it at first appears. You can negate matrices so the problem is one of matrix addition, then rearrange the addition (because addition is commutative):

a - b + c - d  = a + (-b) + c + (-d) 
               = (-d) + a + c + (-b)
               = any rearrangement you want

Some other facts are:

a + (-a) = 0
a - a = 0

Notice that the 0 means the zero matrix, the matrix of the same type as a, but with all elements zero.

( 4, -5, 6.2 ) + ( -43.132, 13.6, 86.5 ) - ( 4, -5, -4.8 ) =