Starting with y=x2, move it left by ADDING 7 to x. (To move x values, we always use the sign opposite the direction that we want to move, so + for left or - for right.) We also put it in parentheses so the whole thing is squared: y=(x+7)2.
To reflect over the y-axis, we want to change the signs of the x values, so we put a negative in front of x: y=(-x+7)2.
Hope this helps!
Let me know if you have any questions, and have fun mathing!