Question

If 3 is added to a number and the sum is tripled, the result is 21 more than the number. Find the number​

Answer 1

9

Explanation:

If 3 is added to the number: x + 3

b) ...and the sum is tripled..

"The sum" is "x + 3" so: 3(x+3)

c) ...the result is 27 more than the number.

27 more than the number is x + 27

d) Put it all together:

3(x + 3) = x + 27

Solve for x:

1) Distribute the left side of the equation:

3x + 9 = x + 27

2) Subtract x from each side of the equation:

2x + 9 = 27

3) Subtract 9 from each side of the equation:

2x = 18

4) Solve for x:

x = 9

Check:

1) x = 9

2) 3(x + 3) = x + 27

3) 3 ([9] + 3) = [9] + 27

4) 3(12) = 9 + 27

5) 36 = 36

Answer 2

Hello there! Hope you are having a nice day! :)

• First of all, let the number be t.
• Add 3 to the number:
• 3+t
• Now, triple the sum:
• 3(3+t)
• Now, the result is 21 more than the number:
• 3(3+t)=t+21
• Now, solve the equation for
  `t`:
• 
  `\longmapsto\sf{3(3+t)=21+t}\\\longmapsto\sf{9+3t=21+t}\\\longmapsto\sf{9+3t-t=21}\\\longmapsto\sf{9+2t=21`
• 
  `\longmapsto\sf{2t=21-9}\\\longmapsto\sf{2t=12}\\\text{Divide both sides by 2 :}`
• 
  `\text{t=6}`

`\huge\fbox{Answer:\:t=6}`

Hope it helps!

`\rm{Stargazing{\bold{WithJoy:D}`