7.31 g cm Your goal when trying to find the density of a given substance is to determine the mass of one unit of volume of that substance.
Option B is a better option.
Step by step:
I divided 40/6.29 and got about 6.3.
I divided 24/3.89 and got about 6.1.
Which is less, 6.3 or 6.1?
If you said 6.1 you are correct, so option B has a less cost, making it a better option.
The rule to use is PEMDAS. (Parenthesis, Exponents, Multiplication, Division, Addition, and Subtraction) When there's a number in front of one parenthesis, you distribute that number to the terms on the inside based on PEMDAS. What should also be notified is the exponent rules for multiplication and division. Then combine like terms. They have to have the same base of multiplying or dividing. Combining like terms need to have the same exponent, or whole numbers in groups.