Answer:
Step-by-step explanation:
<u>Formula:</u> 
The input is the x-coordinate and the output is the y-coordinate. If the input is 4, plug 4 into the x variable to find the output, y.
y=3(4)-5
y=12-5
y=7
The output is 7.
We have two points so we can find the gradient using y1-y2/x1-x2
gradient = 21-27/2-8
= 1
we know the form for any linear equation is y = mx + c
we have m and a point so we can substitute in point (2,21) to find c
21 = 1 x 2 + c
c = 19
therefore, the equation is y = x + 19
