Is my answer correct

Answer:
Yes, you are correct.
Step-by-step explanation:
[tex]\text{Let the number of puzzle solved by Child B is} x\text{.}[/tex]
[tex]\text{Then the average number of puzzle solved is}[/tex]
[tex]\frac{5x+x+(x+4)}{3}=13[/tex]
[tex]\frac{7x+4}{3}=13[/tex]
[tex]7x+4=39[/tex]
[tex]7x=35[/tex]
[tex]x=5[/tex]
[tex]\text{Therefore, the number of puzzles solved by child A is }5x=5\cdot5=25[/tex]
[tex]\color{blue}\text{A little tips here: You can check it by substituting your answer to the original equation.}[/tex]
Answer:
You are correct.
Step-by-step explanation:
[tex]13 \times 3 = 9[/tex]
Child B completed [tex] x [/tex]
Child A = [tex]5x[/tex]
Child C = [tex]x + 4[/tex]
[tex]x + 5x + x + 4 = 39[/tex]
[tex]7x = 35[/tex]
[tex]x = 5[/tex]
Child A = [tex]5 \times 5 = 25[/tex]