Question

MENTAL MATHEMATICS EXERCISE
1. Form the equation for the statement, “3 times a number is 18".
2. Form the equation for the statement, “13 subtracted from 4 times a number is 15.
3. Form an equation for the following:
“49 added to three times a number and the sum divided by 7 gives the result 7".
4. Write a statement for the equation : 4x - 7 = 9.
5. Twice a number when decreased by 7 gives 15, find the number.
6. Solve the equation : -+ 7 = 3.
7. Solve the equation: 2y + 3 = 5y + 7.
78+8
9
8. Solve the equation:
9. A number is as much greater than 21 as it is less than 71. Find the number
1
10. Solve the equation : 5p + 3 = = (p + 1).
| 11. Find three consecutive natural numbers whose sum is 11.
V TEST YOURSELF-6​

Answer 1

1) 3x=18

2) 4x-13=15

3) (49 +3x)÷ 7=17

4) 7 subtracted from 4 times a number gives the result 9

5) 2x-7=15

=> 2x = 22

=> x = 11

6) _ can't be solved since your question is incomplete _

7) 2y + 3 = 5y + 7

=> 3y = -4

=> y = -4/3

8) _ can't be solved since your question is incomplete _

9) let no be x

=> x-21= 71-x

=> 2x = 92

=> x = 46

10)5p + 3 = (p + 1).

=> 4p = -2

=> p = -1/2

11) let the numbers be

a , a+1 ,a+2

=> a+a+1+a+2 =11

=> 3a +3 = 11

=> a = 8/3 = 2 ⅔

=> the three consecutive numbers are 2⅔ , 3⅔,4⅔

Answer 2

Step-by-step explanation:

Hi,

(1) Let the number be X .

Therefore,

3 times of X = 18

3x = 18 [ Answer ]

(2) Let the number be X.

According to the question,

13 subtracted from 4 time's a number is 15.

Therefore,

4X - 13 = 15 [ Answer ]

(3) Let the number be X.

According to the question,

When 49 is added to 3 times a number and the sum divide by 7 gives the result 7.

Therefore,

3X + 49 / 7 = 7

3x + 49 = 7 × 7

3x + 49 = 49 [ Answer ]

(4) When 7 is subtracted from 4 times a number gives the result 9.

(5) Let the number be X.

According to the question,

Twice a number when decreased By 7 gives 15.

Therefore,

2X - 7 = 15

2x = 15 + 7

2x = 22

X = 22/2

X = 11.

Hence,

The number is 11 [ Answer ]

(6) X + 7 = 3

=> X = 3 - 7

=> X = -4 [ Answer ]

(7) 5P + 3 = P + 1

=> 5P - P = 1 - 3

=> 4P = -2

=> P = -2/4

=> P = -1/2 [ Answer ]

(8) Let three consecutive numbers be X , X + 1 and X + 2.

According to the question,

X + X + 1 + X + 2 = 11

3x + 3 = 11

3x = 11 - 3

3x = 8

X = 8/3.

Therefore,

First number = X = 8/3

Second number = X + 1 = 8/3 + 1 = 11/3

And,

Third number = X + 2 = 8/3 + 2 = 14/3 .

Hope it will help you :)