Each student ticket for an art museum costs $12.50. The total cost for student tickets, t, varies directly as the number of tickets, s, purchased. Write an equation that models the proportional relationship between t and s.

First step is to get rid of the square root. remember that a square root is the same as raising to the (1/2) power. see below: multiply exponents per exponent rules to get: remember you subtract exponents from the denominator and add exponents in the numerator so: simplify further: so a is the correct choice. if you don't understand this google exponent rules and it will you understand. look at the image results.