What’s the answer to this

slope: -1/3

you find the slope by taking one point (0,2) and then finding the change in y over the change in x from it to another point (3,1) :

1-2/(3-0) = -1/3

check above link.

graphically?   well, you graph them both, the solutions is where they both intersect each other, since there are two solutions, meaning they will meet twice, or namely the linear will run into the quadratic curve twice, and where they meet, those x,y coordinates are the solutions to the system.

answer: given the scale 3,5 mm to 1 foot: so you know this and you need convert this 150mm to get the right answer.