2x + Y = 1300

and your question is?

well, there is many ways you can do this, for example let x=630 and y=40 so the statment would read 2times 630 plus 40 = 1300
2X630+40=1300

Algebraically solve as one would with an equation of two variables. Solve for y in terms of x or solve for x in terms of y. Isolate according to which of the two procedures comes out most cleanly. Plug the expression back in and you can solve the equation thusly by substitution. Also, this easily can be thought of as being a line graph in slope/ y-intercept form y= negative 2x + 1300 or y= 1300-2x. Finally, one can approach this by intercepts (when x=0, y=?, when y=0, x=?).