Answer
(x, 3) (y, 6) (z, 4) (A, 2) (x, 4) Compression ratio = 1.8:1
Work Step by Step
The text will be converted to (x, 3) (y, 6) (z, 4) (A, 2) (x, 4) which will take 80 bits (10 characters of 8 bit each). Without compression it will take 144 bits (18 characters of 8 bits each).
Compression ratio = $\frac{uncompressed\space size}{compressed \space size} = \frac{144}{80}=1.8$
=> Compression ratio = 1.8:1
