15x + 4y = 61 ---(1)4x + 15y = 72 ---(2)Adding (1) and (2)(15+4)x + (15+4)y = 61+72=> 19(x+y) = 133 => x+y = 133/19 = 7--(3)Subtracting (1) and (2)(15-4)x + (4-15)y = 61-72=> 11x - 11y = -11 => 11(x-y) = -11= x-y = -11 --(4)From (3) and (4) x + y = 7x - y = -11--------------2X = -4 => x = -2=> y= 7-x = 7+2 = 9
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