9514 1404 393
Answer:
$105
Step-by-step explanation:
The thicker wall takes 345 -205 = 140 more blocks. Each of those costs $0.75, so the added blocks will cost ...
140 × $0.75 = $105
The thicker wall will cost $105 more.
When working with very large or very small numbers, scientists, mathematicians, and engineers use scientific notation to express these quantities. Scientific notation is a mathematical abbreviation, based on the idea that it is easier to read an exponent than to count many zeros in a number. Very large or very small numbers need less space when written in scientific notation because the position values are expressed as powers of 10. Calculations with long numbers are easier to do when using scientific notation
Answer:

It is 9

Step-by-step explanation:

If the top and the bottom are the same, (shown in the larger model), then the top and bottom in the smaller model should be the same, which gives me 9.

Good luck!
460 is your answer
20 x 23 = 460