Let x be the number of sweets one had, and y be the number of sweets the other had.........
then;
x = 2y...................................... (i)
after each eating one, they remain with (x - 1) and (y - 1)
So;
x - 1 = 3(y - 1)
= 3y - 3
so; x = 3y - 2.................. (ii)
substitute eqn (i) into eqn (ii), we have;
2y = 3y - 2
Which means; y = 2...............(iii)
applying eqn (iii) to eqn (i)................ eqn (i) becomes
x = 2 (2)
= 4.
Therefore; one had 4 sweets and thhe other had 2 sweets.
