3x - 5y = 20
6x - 10y = 40
a1a2=36=12
b1b2=−5−10=12
c1c2=−20−40=12
a1a2=b1b2=c1c2
Therefore, the given sets of lines will be overlapping each other i.e., the lines will be coincident to each other.
Thus, there are infinite solutions possible for these equations.