= 315 ====> (x-y)*(x+y) = 315 ====> replace (x-y) by 35, based on the condition. You will get 35*(x+y) = 315 ====> x + y = = 9. Thus you reduced the given non-linear system to the simple LINEAR one, consisting of two equations x - y = 35, x + y = 9. -------------------Add the two equations. You will get 2x = 35 + 9 = 44 ====> x = = 22. One number is 22. Then the other is y = 22 - 35 = -13. Check. = 315. ! Correct ! Answer. The numbers are 22 and -13.