You would is this case use the perfect square rule. So your would squareroot 9r^2 and 25 to get 3r+5 then you would square this equation to get (3r+5)^2
I hope this helps you
42=1.42
42= 2.3.7
42= 6.7
40% of 65.00=0.40×65=26
65-26=39(your price)
sales tax(5%)=0.05×39=1.95 tax
39+1.95
=40.95(total)