Slope: 3, y-intercept; 10

y = 3x + 10

Step-by-step explanation:

Given that,

Slope = 3

y intercept = 10

We need to write an equation of a line.

The slope-intercept form of a linear equation is given by :  

y = mx + b

Where

m is slope and b is y-intercept

Putting all the given values,

y = 3x + 10

Hence, the required equation is "y = 3x + 10"

x = -3

y = -18

step-by-step explanation:

to solve by substitution, substitute one variable and solve for the other. then substitute again to find the remaining variable.

x-1/3(3x-9) = -3 since y=3x-9 substittute y.

x-1/3(3x-9)=-3

x + x +3 = -3

2x+3=-3

2x+3-3= -3-3

2x=-6

x=-3

substitute again into y=3x-9

y=3(-3)-9

y=-9-9

y=-18