PLZ ASAP IM IN A TIMED QUIZ What is the solution to the system of equations below?

x + 3 y = 15 and 4 x + 2 y = 30

The area of a rectangle is 54x^9y^8 square yards.if the length of the rectangle is 6x^3y^4 yards,which expression represents the width of the rectangle in yards

He mass of a single atom of carbon can be found by dividing the atomic mass (12.01 g) by 6.022 x 10^23. which is the mass of a single carbon atom, correctly written in scientific notation with the correct number of significant figures?

Astore is having a sale in which all items are reduced by 20 percent. including tax, jennifer paid $21 for a pair of shorts. if the sales tax is 5 percent, what was the original price of the shorts