Following thread we have :

An item with original price : d dollars.

+ In April : \(d\cdot\left(100\%+x\%\right)=d'\)

+ In May : \(\dfrac{d'}{100\%}\cdot\left(100\%-x\%\right)=d''\)

The resulting price is : \(d''=\left(100\%-4\%\right)\cdot d\)

The same with : \(\dfrac{d'}{100\%}\cdot\left(100\%-x\%\right)=96\%\cdot\left(\dfrac{d'}{100\%+x\%}\right)\)

Solve the equation we have x = 20.

So the answer is x = 20.

Multiple of 91 <=> Divisible by 91.

We have: \(abc⋮d\) => \(abcabc⋮d\)

=> \(5ab⋮91\) => \(546⋮91\)

So the number is: 546

The smallest odd between 20 and 158 is 21

The greatest odd between 20 and 158 is 157

So the number of odd between 20 and 158 is:

\(\dfrac{157-21}{2}+1=69\left(odd-numbers\right)\)

So there are 69 odd number between 20 and 158

The smallest odd greater than 20 is: 21
The largest number less than 158 is 157
Odd numbers are:

(157-21): 2 + 1 = 69 (odds)

Answer: 69 odds

Smaller numbers greater than 20 are: 21
The largest number less than 158 is 157
Odd numbers are:

(157-21):2+1=69

Answer:69

The first number:3=1.3

The second number:6=3.2

The third number:9=3.3

.........

So the 99th number of row is:

   3.99=297

Answer:297

1st = 1.3

2nd = 2.3

3rd = 3.3

............

=> 99th = 99.3 = 297

ANSWER:

In a standard deck of 52 playing cards, the red number cards greater than 6 are the 7, 8, 9 and 10 in the suits of diamonds and hearts. That’s a total of 8 cards. The percent probability that Perta randomly selects one of these 8 cards, then, is 8/52 ≈ 15.38%.

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Call three two-digit prime number is a, b and c.

Suppose: a < b < c

We have: \(\left\{{}\begin{matrix}c=43\\b-a=10\end{matrix}\right.\)

But a + b + c = 79 => a + b = 36.

=> b = ( 36 + 10 ) : 2 = 23 

=> a = 23 - 10 = 13 

=> a x b x c = 23 x 13 x 43 = 12857