Pablo took out an 80/20 mortgage to buy a house that cost $140,000. The first
(80%) mortgage has an interest rate of 4.75%, and the second (20%) mortgage
has an interest rate of 7.525%. Both the first mortgage and the second mortgage
are 30-year fixed-rate mortgages. What is the total monthly mortgage payment
for the house?

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.