a - b = 54
a : b = 6 rest 4 ⇒a = 6b + 4
~~~~~~~~~~~~~~~~~
a, b = ?
6b + 4 - b = 54
5b + 4 = 54
5b = 54- 4 = 50
b = 50 : 5 = 10.
a = 6b + 4
a = 6 · 10 + 4 = 64.
@robertinnifd