The set of integers is closed under addition, subtraction, and multiplication because when i add, subtract, or multiply any integers, the result is always an integer.
The tens digit is 8 more than the ones digit. There isn't any zeros.
The maximum digit is 9 because 10 would be 2 digits, 1 and 0.
So say the tens digits is 9.
9 _
The ones digit is 8 less so 9-8 = 1
9 1
There isn't any zeros which is correct.
The answer is 91.
Answer:
r = 2
Step-by-step explanation:
2(8r + 5) = 24 + 9r
16r + 10 = 24 + 9r
16r - 9r = 24 - 10
7r = 14
r = 2
Step-by-step explanation:
To multiply the fractions, like

Multiply the top,
then multiply the bottom.

Try to use a calculator if you aren't arithmetic heavy, but I suggest you to try to remember them because they are going to be helpful for courses like Algebra, Calculus, Statistics, etc.
To divide fractions, like

You take the top number,

Then you flip the bottom number,

Then multiply the two

And that is your answer. Comment if you need more clarification
The answer is A because Alon could have rotated the figure and discovered that they are congruent