I need to find the pair of matrices that are inverses, but I don't fully understand how to inverse matrices.

P = [3 1_-4 0] q = [4 4_12 21]

R = [0 -1/4_1 3/4]

S = [7/12 -1/9_-1/3 1/9]

T = [4 -5 2_8 -1 3]

U = [-9 6 4_-5 -2 3]

V = [3 1_0 2_-4 5]

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answer choices:

a. S and R

b. Q and R

c. P and Q

d. Q and S

if you could explain it to me that would be great, thanks.