5.

1/3 part of salary = $390

Total salary = $390*3/1 = $1170

Amount given to parents = $1170*4/9 = $520

Remaining money = Total salary - Spending on food - Amount given to parents

= $1170 - $390 - $520 = $260

Amount saved = 1/2 of remaining money

= $260*1/2 = $130

Money saved = $130

6.

Let, the cost of each chocolate bar = x

Cost of each pack of potato chips = y

so,

=> 5x + 6y = 2/9 * 243

=> 5x +6y =54............(i)

and,

=> 3y = 2x

=> y = 2/3x................(ii)

Substituting value of y in (i):

=> 5x + 6(2/3x) = 54

=> 5x + 4x = 54

=> 9x = 54

=> x = 54/9

=> x = 6

Substituting value of x in (ii):

=> y = 2/3(6)

=> y = 4

So,

Cost of each chocolate bar = $6

Cost of each pack of potato chips = $4

Amount of money left = (1 - 2/9) * 243 = 7/9 * 243 = $189

Finding greatest number of chocolate bars he cay buy:

=> 189/6

=> 31.5

so,

Greatest number of chocolate bars he cay buy = 31