Question

4- Thrice a number increased by 6 equal 39. Find the number.5- Three-fourths of a number exceed its one-third by 15. Find the number.6- A number when divided by 4 is reduced by 21. Find the number. [Hint. Let the required number be x then x/4=(x-21)]7- A number is as much greater than 36 as is less than 86. Find the number. [Hint. Let the required number x. Then x-36 =86-.]8- A number exceeds it’s four-sevenths by 18. Find the number.9- A number exceed 20% of itself by 40. Find the number.10- If 10 be added to four times a certain number, the result is 5 less than five time. Find the number.

Answer 1

Let the number be x in all the cases
4. 3x+6=39
3x=39-6
3x=33
x=33/3=11

5. 3/4x=1/3x+15
3/4x - 1/3x=15
5/12x=15
5x=15×12
x=15×12/5=3×12=36

6. x/4=x-21
x/4 - x= -21
-3x/4= -21
-3x= -21×4
x= -21×4/-3=28

7. x-36=86-x
x+x=86+36
2x=122
x=122/2=61

8. x=4/7x+18
x-4/7x=18
3x/7=18
3x=18×7
x=18×7/3=6×7=42

9. x=20/100x+40
x=1/5x+40
x-1/5x=40
4x/5=40
4x=40×5
x=40×5/4=10×5=50

10. 4x+10=5x-5
4x-5x= -5-10
-x= -15
x=15