Use PEMDAS (Parentheses, Exponents, Multipy/Divide, Add/Subtract):

2 + (4 + 3) ÷ 4 x 5 - 3²
P: 2 + (7) ÷ 4 x 5 - 3²
E: 2 + 7 ÷ 4 x 5 - 9
MD: 2 + \( \frac{7}{4} \) x 5 - 9
MD: 2 + \( \frac{35}{4} \) - 9
AS: \( \frac{8}{4} \) + \( \frac{35}{4} \) - 9
AS: \( \frac{43}{4} \) - 9
AS: \( \frac{43 - 36}{4} \)
\( \frac{7}{4} \)
1\(\frac{3}{4}\)

To simplify this fraction, first find the greatest common factor between them. The factors of 28 are [1, 2, 4, 7, 14, 28] and the factors of 68 are [1, 2, 4, 17, 34, 68]. They share 3 factors [1, 2, 4] making 4 their greatest common factor (GCF).

Next, divide both numerator and denominator by the GCF:

\( \frac{28}{68} \) = \( \frac{\frac{28}{4}}{\frac{68}{4}} \) = \( \frac{7}{17} \)

To fill a 25 gallon tank exactly halfway you'll need 12\(\frac{1}{2}\) gallons of fuel. Each fuel can holds 2\(\frac{1}{2}\) gallons so:

cans = \( \frac{12\frac{1}{2} \text{ gallons}}{2\frac{1}{2} \text{ gallons}} \) = 5

A prime number is an integer greater than 1 that has no factors other than 1 and itself. Examples of prime numbers include 2, 3, 5, 7, and 11.

To find the average of these 4 numbers add them together then divide by 4:

\( \frac{17 + 13 + 18 + 12}{4} \) = \( \frac{60}{4} \) = 15