The equation of a line is according to a formula, y = mx+b where m is the slope and b is the y intercept
You can find the full equation of the line using a point on it if you also know the slope, because you can plug in the point into the equation (for the x and y spots) to find the y intercept
So, plugging in all the info you have -
4 = 6(3) + b
You then just have to solve for b.
4 = 18 + b
subtract 18 from both sides
-14 = b
b, the y-intercept, is -14. So the full equation of the line is y = 6x-14.
Then, to find y when x=27, you just plug in 27 for x and solve again.
y = 6(27) - 14
y = 148
