80% of what number is 64

Lydia bought a shirt at 20% off its retail price of $40. She paid a 5% tax on the price after the discount. How much did Lydia pay for the shirt?

A secret code consist of 3 digits from 0 to 9 followed by 2 letters from 'A' to 'Z'. None of the digits or letters repeat. How many secret codes are possible?

Triangle QRS is a right triangle with the right angle at vertex R. The sum of m∠Q and m∠S must be equal to 45°. greater than 45° and less than 90°. equal to 90°. greater than 90° and less than 180°.

A tractor costs $12,250 and depreciates by 6% per years. How much will the tractor be worth after 6 years?

Pedro has the function f (x) = 4x-3/2

A newspaper reporter wants to know how popular the hobby of bird watching is in the city. He asked people at the local bird refuge if they watched birds as a hobby. Which of the following best explains whether the reporters data is valid or not?

I am very confused on how to figure out if y = 3/4x is proportional?

Alison wants to buy a mountain bike for $339.12. If she saves $28.26 each month, in how many months will she be able to buy the bike?

At 12 o'clock the temperature was 7°C. The temperature decreased by - 20°C. What is the new temperature?

Ashleys rentals charges $27.50 per hour to rent a surfboard and a wetsuit. Darlas surf shop charges $23.25 per hour to rent a surfboard plus $17 extra for a wetsuit.