For these problems you have to use PEMDAS so for problem 15 you would do the parentheses first, (21-3) you get 18 and then exponents, 3^2, you get 9, no multiplication but there is division so take your answers, 18 and 9 and divide them, you get 2, so the answer to 15 is 2.
Im a little confused here because there isn't enough information to go on or I might be reading it wrong.
Answer:
<h2>
x = 15</h2>
Step-by-step explanation:
RQ < PR < PQ
TV < UV < UT
ΔPQR~ΔUTV ⇒ 

Answer:
the second one
Step-by-step explanation:
He spent $5.80.
1 x 4/5 = 0.8
1 x 5 = 5