Answer:
n = 12, she has played 12 games
Step-by-step explanation:
40 = 16 + 2n
24 = 2n
24/2 = n
n = 12
x=10,y=5,z=2
x+15=2x+5
x=10
4y=8y-20
4y=20
y=5
10z-5=3z+9
7z=14
z=2
