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.