set up 2 equations with variables - x is the 1st game score and y is the second game score
x + y = 35
6x = y
Since you know 6x = y, now just pop 6x in for the y in the 1st equation you set up
6x + x = 35
7x = 35
x = 5
Then if x is 5, y is 30 (put it in either equation to find that)
So she scored 25 more points in the 2nd game