Let the three numbers be x, y and z x + y = 55 ......(i) y + z = 65 ......(ii) 3x + z = 110 ......(iii) From subtracting (ii) from (i), z - x = 10 ......(iv) Subtracting (iv) from (iii), 4x = 100 x = 25 From equation (iii), substitute the value of x = 25 3( 25) + z = 110 z = 110 -75 z = 35