What are the main parts of writing a proof?

Wrote and expression for the difference of p and 4

$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

For what values of a is the sum of the fractions 2a−1 / 4 and a−1 /3 positive?