Answer:
A definition and a theorem can be used as a reason in a two-column proof. A two column proof is assembled into statement and reason columns, where each statement should have verified reason.
Step-by-step explanation:
3 and -3 are said to be the square roots of 9. A square root is written with a radical symbol √ and the number or expression inside the radical symbol, below denoted a, is called the radicand. ... Negative numbers don't have real square roots since a square is either positive or 0.
The Answer would be x=72. Why? Because

is your %. You Cross multiply 240 * 30 = 100x
240 time 30 = 7200. you want x to be alone so you do 7200 divided by 100 equaling 72. So you get x=72.
1) 55% is girls, then
100-55=45% is boys.
2) 45%=0.45 or 2) 400 ----100%
3)400*0.45= 180 boys x -----45% x=400*45/100=180 boys
Answer is 180 boys.