Monday, November 12, 2012

The Sum of Twice a Number and Seven

The sum of twice a number and seven :

In general ,twice means a number multiplied by 2 .the sum of twice a number means a number multiplied by 2 +7.in other words,Sum of twice a number and seven means ,the product of  number by 2  plus seven.

For example : Let us consider the unknown number x,y,z, The expression should becomes 2x+7,2y+7,2z+7

Example Problems to Find Sum of Twice a Number and Seven :
Example 1:

The sum of twice a number and seven is 19.Find the number ?

Solution:

The sum of twice a number and 7 is 19.

Let us consider the unknown number is x,

Write this sentence into equation,we get,

2x+7 =19

Subtract 7 on both sides, 2x+7-7=19-7

2x=12

Divide both sides by 2,x=`12/2`

x=6

Therefore the unknown number x=6

Example 2:

The sum of twice a number and seven is 17.Find the number ?

Solution:

The sum of twice a number and 7 is 17.

Let us consider the unknown number is x,

Write this sentence into equation,we get,

2x+7 =17

Subtract 7 on both sides, 2x+7-7=17-7

2x=10

Divide both sides by 2,x=`10/2`

x=5

Therefore the unknown number x=5

Example 3:

The sum of twice a number and seven is 53.Find the number ?

Solution:

The sum of twice a number and 7 is 53Let us consider the unknown number is x,

Write this sentence into equation,we get,

2x+7 =53

Subtract 7 on both sides, 2x+7-7=53-7

2x=46

Divide both sides by 2,x=`46/2`

x=23

Therefore the unknown number x=23

Example 4:

The sum of twice a number and seven is 121.Find the number ?

Solution:

The sum of twice a number and 7 is 121

Let us consider the unknown number is x,

Write this sentence into equation,we get,

2x+7 =121

Subtract 7 on both sides, 2x+7-7=121-7

2x=114

Divide both sides by 2,x=`114/2`

x=57

Therefore the unknown number x=57

Please express your views of this topic What is a Composite Number? by commenting on blog.

Practice Problem to Find the Sum of Twice a Number and Seven:

1)The sum of twice a number and seven is 13.Find the number ?

Answer:3

2)The sum of twice a number and seven is 25.Find the number ?

Answer:9

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