I need help in this one

Olivia uses the work below to determine 55% of 720 which explains the error in olivia’s solution

$30 to spend on dinner tax and gratuity at mos restaurant rax is 6% and they give a 15% tip on the total bill after taxes thier dinner cost $21 which statement correctly explains wether andrew and kate have enough money to pay their bill

1.multiply and simplify if possible. √7x (√x − 7√7) 2. what is the simplest form of the radical expression? 33√2a−63√2a