Let second no = x ----------(1)
first no = twice the second no - 43;(given)
=2x -43 ----------------(2)
sum of the no = 50;
first no + second no = 50 ---------(3)
2x - 43 + x = 50 [ substituting (1) and (2) in (3)]
3x -43 = 50
3x = 50 + 43
3x = 93
x = 93 /3
x = 31;
substitute x = 31 in (2)
first no = 2x -43
= 2*31 - 43
= 62 - 43
=19
first no = 19
second no = 31