2/3x - 1/2y = 3
1/2x + y = 5
which of the following systems is equivalent to the given system?
2x - y = 18 and x + 2y = 10
4x - 3y = 18 and x + 2y = 10
2x - 3y = 3 and x + 2y = 5

The correct answer for this question would be the second option. 4x - 3y = 18 and x + 2y = 10. So in order to know why this is the answer, let us check it. Since the given numbers have fractions, let us eliminate the fractions.
2/3x - 1/2 y = 3 <<multiply both sides by 6
and we get 4x - 3y = 18 (So this one is correct)
Next,
1/2x + y = 5 << multiply both sides by 2 and we get
x + 2y = 10 (This one is correct too)
Hope this answer helps.