Multiplicative property of equality states that if a and b are 2 equal expressions, or numbers, then if we multiply both by a non zero expression c, then the results are again equal.
So if a=b, then ac=bc.
The first equality is
(i)

multiplying both sides by 12, we have:

3x+4y=60
The second equality is

multiplying by 2 we get
x+3y=22
Answer: 3x+4y=60; x+3y=22 (the first one only)