In one city, customers must pay 6% on all items purchased. the video game controllers cost $18.50 each. if a customer purchases 2 controllers, how much tax will she pay?

6n^2-7n-75=0 solve by quadratic formula

Evaluate the expression for the given value of the variable 2×(c2-5) for c=4

Offering 30 if a plus b plus c equals 68 and ab plus bc plus ca equals 1121, where a, b, and c are all prime numbers, find the value of abc. the answer is 1978 but i need an explanation on how to get that.