A house wife forgot her bank ATM PIN which is
a four digit number, but luckily she remembered
some hints on how to recall this "PIN
Here are some of the clues
(1) The 1st digit is half of the 2nd
(2) The sum of the 2nd and 3rd is 9
(3) The 4th is equal to the 2nd minus 1
(4) The sum of all the digits is 17
What is the ATM PIN ?

The ATM pin is 3635

Step-by-step explanation:

Let the first digit be 'a'

Second digit be 'b'

Third digit be 'c'

Fourth digit be 'd'

Some hints are given,

a = b/2

b + c = 9

d = b - 1

a + b + c + d = 17

a + b + c + d = 17

a + 9 + d = 17

a + d = 8

d = b-1

a = b/2

b + c = 9

So,

a + b + c + d = 17

b/2 + 9 + b-1 = 17

b/2 + b + 8 = 17

3b/2 = 9

3b = 18

b = 6

a = b/2

a = 6/2

a = 3

b + c = 9

6+c = 9

c = 3

d = b - 1

d = 6-1

d = 5

So,

a = 3

b = 6

c = 3

d = 5

So the ATM pin is 3635

the perimeter is increased by a factor of 2

walter needs to make at least 5 more cookies but no more than 40. 5 ≤ x ≤ 40

step-by-step explanation:

20 ≤ x + 15 ≤ 55

subtract 15 from all parts

20-15 ≤ x + 15-15 ≤ 55-15

5 ≤ x ≤ 40

this means how many more cookies he has to make

walter needs to make at least 5 more cookies, but no more than 40 cookies; 5 ≤ x ≤ 40