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Veseljchak [2.6K]
3 years ago
15

On his bookshelf, Adam has the difference between two-thirds of Brett's books and two-thirds of Charlie's books. If Brett has 84

books and Charlie has 27 books, how many books does Adam have?
Mathematics
1 answer:
Gala2k [10]3 years ago
7 0

Answer:

30 books

Step-by-step explanation:

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A hat's original price was $50. It is on sale for 40%0ff. How much does it cost?
yKpoI14uk [10]

Answer:

30

Step-by-step explanation:

40/100 x 50= 20

50-20=30

3 0
2 years ago
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1. Prove or give a counterexample for the following statements: a) If ff: AA → BB is an injective function and bb ∈ BB, then |ff
Fantom [35]

Answer:

a) False. A = {1}, B = {1,2} f: A ⇒ B, f(1) = 1

b) True

c) True

d) B = {1}, A = N, f: N ⇒ {1}, f(x) = 1

Step-by-step explanation:

a) lets use A = {1}, B = {1,2} f: A ⇒ B, f(1) = 1. Here f is injective but 2 is an element of b and |f−¹({b})| = 0., not 1. This statement is False.

b) This is True. If  A were finite, then it can only be bijective with another finite set with equal cardinal, therefore, B should be finite (and with equal cardinal). If A were not finite but countable, then there should exist a bijection g: N ⇒ A, where N is the set of natural numbers. Note that f o g : N ⇒ B is a bijection because it is composition of bijections. This, B should be countable. This statement is True.

c) This is true, if f were surjective, then for every element of B there should exist an element a in A such that f(a) = b. This means that  f−¹({b}) has positive cardinal for each element b from B. since f⁻¹(b) ∩ f⁻¹(b') = ∅ for different elements b and b' (because an element of A cant return two different values with f). Therefore, each element of B can be assigned to a subset of A (f⁻¹(b)), with cardinal at least 1, this means that |B| ≤ |A|, and as a consequence, B is finite.

b) This is false, B = {1} is finite, A = N is infinite, however if f: N ⇒ {1}, f(x) = 1 for any natural number x, then f is surjective despite A not being finite.

4 0
3 years ago
Find the measure of
maks197457 [2]

Answer:

119 is the answer

Step-by-step explanation:

use sum of angles on a straight line

5 0
3 years ago
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What is 1.6 powered by 2
ss7ja [257]

Answer:

2.56

Step-by-step explanation:

1.6^2 = 1.6 * 1.6 = 2.56

7 0
3 years ago
I need the top if you don’t know pls don’t answer
mr_godi [17]

Answer:

its 45 degrees celcius

Step-by-step explanation:

7 0
2 years ago
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