Adrawer contains 15 cents stamps and 18 cent stamps the number of 15 cent stamps is four less that three times the number of 18 cent stamps the total value of all the stamps is 1.29 dollars . how many 15 cent stamps are in the drawer

there are 5 15 cents stamps in the drawer.

Step-by-step explanation:

The drawer contains 15 cents stamps and 18 cent stamps.

Let x represent the number of 15 cents stamps that is inside the drawer.

Let y represent the number of 18 cents stamps that is inside the drawer.

the number of 15 cent stamps is four less than three times the number of 18 cent stamps. This means that

x = 3y - 4

The total value of all the stamps is 1.29 dollars. Converting 1.29 dollars to cents, it becomes 1.29×100 = 129 cents.

Therefore

15x + 18y = 129 - - - - - - - - - - -1

Substituting x = 3y - 4 into equation 1, it becomes

15(3y - 4) + 18y = 129

45y - 60 + 18y = 129

45y + 18y = 129 + 60

63y = 189

y = 189/63 = 3

substituting y = 3 into x = 3y - 4, it becomes

x = 3×3 - 4 = 9-4 = 5

it costs $20 to interview each person for a survey. find the cost to obtain a +- 3% margin of error.

step-by-step explanation:

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h/o/e/s mad

step-by-step explanation:

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