What is the total cost or it is unsolvable?
7/9 = 42/54...when 42/54 reduces, it becomes 7/9...so this is proportional because proportions are nothing but equivalent fractions.
u could also check it this way...
12/21 = 15/24
cross multiply
(21)(15) = (12)(24)
315 = 288.....these do not equal and are therefore, not proportionate
440/4 = 300/3
110 = 100....not equal, so not proportionate
120/5 = 88/4
24 = 22.....not proportionate
66/82 = 99/123
0.804 = 0.804.......these are proportional
68/172 = 43/123
0.395 = 0.349......nope, not proportional
The answer would be

or 27.7 km²
if rounded to the nearest tenth
Answer:
z = -9
General Formulas and Concepts:
<u>Pre-Algebra</u>
Order of Operations: BPEMDAS
- Brackets
- Parenthesis
- Exponents
- Multiplication
- Division
- Addition
- Subtraction
Equality Properties
<u>Algebra I</u>
- Terms/Coefficients/Degrees
Step-by-step explanation:
<u>Step 1: Define</u>
-21 = z - (-6 - 2z)
<u>Step 2: Solve for </u><u><em>z</em></u>
- Distribute negative: -21 = z + 6 + 2z
- Combine like terms: -21 = 3z + 6
- Isolate <em>z</em> term: -27 = 3z
- Isolate <em>z</em>: -9 = z
- Rewrite: z = -9