Write √80 in the form c√5, where c is a positive integer.

Firstly, we recall that √ab=√a x √b. Noticing that 80=16 x 5 then, we have that √80=√16 x √5. Since √16 = 4 then, we have that √80=4 x √5. So, giving the final answer in the form that the question asks: c=4, which is a positive integer (positive means greater than zero, integer means whole number, i.e. not a fraction or decimal).