Answer:
D x+9 = 2x+1
Explanation:
y = x+9
y = 2x+1
Substitute x+9 for y in the second equation
y = 2x+1
x+9 = 2x+1
This answers the question
To finish the problem
Subtract x from each side
x+9-x =2x-x+1
9 = x+1
Subtract 1 from each side
9-1 =x+1-1
8=x
Now find y
y = x+9
y = 8+9
y=17