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26 votes
26 votes
Find two numbers such that one number is 3 less than twice as big as the other number and the two numbers sum to 21.

User Giraldi
by
2.9k points

2 Answers

20 votes
20 votes

Final answer:

the two numbers are 13 and 8. To find the two numbers, we can set up two equations based on the given information and solve them simultaneously.

Step-by-step explanation:

Let's assume the first number is x and the second number is y.

According to the given information, one number is 3 less than twice as big as the other number. This can be expressed as follows:

x = 2y - 3

The sum of the two numbers is 21, so we can write the equation:

x + y = 21

Substituting the value of x from the first equation into the second equation:

(2y - 3) + y = 21

Combining like terms:

3y - 3 = 21

Adding 3 to both sides:

3y = 24

Dividing both sides by 3:

y = 8

Substituting the value of y back into the first equation:

x = 2(8) - 3

x = 13

Therefore, the two numbers are 13 and 8.

User Matthiasgiger
by
2.9k points
14 votes
14 votes

Answer:

The two numbers are:

8 and 13

Step-by-step explanation:

a = 2b - 3 Eq. 1

a + b = 21 Eq. 2

Replacing Eq. 1 in Eq. 2:

(2b-3) + b = 21

3b - 3 = 21

3b = 21 + 3

3b = 24

b = 24/3

b = 8

from Eq. 1

a = 2*8 - 3

a = 16 - 3

a = 13

Check:

From Eq. 2:

a + b = 21

13 + 8 = 21

User EpiX
by
2.8k points
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