Answer:
x=-7
Explanation:
If a line is parallel to the y-axis, then it is vertical because the y-axis is vertical.
A vertical line is in the form of x=a number.
Since the line we are looking for is 7 units to the left of the y-axis, then the line is x=-7. -7 is 7 units left of 0.
7 units right would have been x=7.