If I translated correctly into my native language, then you need to write the equation of the straight line.
y=x this is a straight line through the first and third quarters.
1) multiply by 2: y= 2x
2) to raise the function by 3 units, you need to add 3 to it. For example: y=2x to bring it up: y=2x+3
It is about 98.6666 hope i helped
3/4 (x+8)=9
3/4x+6=9
-6
3/4x=3
X=4
Check
3/4(4+8)=9
3/4 (12)=9
9=9