Find the discriminant of
x^2 -x+7=0

Scarlet bought three pairs of sunglasses and two shirts for $81 and paula bought one pair of sunglasses and five shirts for $105 what is the cost of one pair of sunglasses and one shirt?

For what value of (y) is 3^3/3^y =1/9

The sales tax for an item was $8.40 and it cost $420 before tax. find the sales tax rate. write your answer as a percentage.