At Super Grocery, potatoes cost $2.85 for 5 pounds. At Value Market, potatoes cost $4.20 for 7 pounds. What is the unit price of a pound of potatoes at Value Market?

The scale factor of what ?

First step is to get rid of the square root. remember that a square root is the same as raising to the (1/2) power. see below: multiply exponents per exponent rules to get: remember you subtract exponents from the denominator and add exponents in the numerator so: simplify further: so a is the correct choice. if you don't understand this google exponent rules and it will you understand. look at the image results.