2. let the input cost be z.
Then z = 50x+35 (700-x) = 24500+15x.
Because z≥30000
So 24500+ 15x≥30000.
So x≥366.7
Because x must be an integer.
So x≥367
So y =10500+5x ≥10500+5x367 =12335.
So at least the profit is 12335.