Gradient of line= (y2-y1)/(x2-x1)
Gradient of line= (10-(-6))/(8-4)
Gradient of line= 16/4
Gradient of line= 4
Y-intercept
Y=4x+c
When x=8, y=10
10=32+c
c= -22
Equation of line
Y=4x-22
When x=b, y=2b
Y=4x-22
2b=4b-22
22=2b
b=11
The answer is 9 because there both divisible by 9
X is 6.11431
so 6.1 rounded to nearest tenth