Using Euclid's division algorithm,
153 = 85 x 2 + 68
85 = 68 x 1 + 17
68 = 17 x 4 + 0
Since the remainder has Come to zero, So the HCF of given numbers is 17.
From given data HCF is written as:
85m - 238 = 17
85m = 17 + 238
85m = 255
\(m = \frac {255}{85}\)
\(\therefore\) m = 3