I need help please. will mark brainest if correct

Brent paid for 6 avocados with a $20.00 bill. he received $10.40 in change. construct and solve an equation can be used to find the price , of each avocados

Im so bad at fractions they are not my best math thing to work on

Apossible wavelength for the color blue is 0.000000492 meter. which of the following is a reasonable estimate for this wavelength for the color blue? a. 5 × 10-6 m b. 5 × 107 m c. 5 × 10-7 m d. 5 × 106 m