I will create a set of arbitrary constants (x1,y1) (x2,y2)
slope = y2-y1/x2-x1
y = (y2-y1/x2-x1)x + b
y2 = (y2-y1/x2-x1)x2 + b
b = y2 - (y2-y1/x2-x1)x2
y = (y2-y1/x2-x1)x + [y2 - (y2-y1/x2-x1)]
Choose any points and just
Plug the values and you have a linear function.
NOT SURE IF THAT'S WHAT THE QUESTION WANTS.
a+b=350 => a=350 - b
3a + 5b = 1450
3(350-b)+b=1450
1050-3b+5b=1450
2b=400
b=200
a=150
Explanation is in the file
tinyurl.com/wpazsebu