contestada

You have been asked to set up chairs for the school concert. The first row will have 10 seats, and each additional row has 4 seats more than the previous row. How many seats are there in row 20?

Respuesta :

Hello!

This is a question about an arithmetic sequence. We can solve it using the formula:

[tex]a_n=a_1+(n-1)\cdot r[/tex]

Let's replace them with the values mentioned in the exercise:

[tex]\begin{gathered} a_{20}=10+(20-1)\cdot4 \\ a_{20}=10+19\cdot4 \\ a_{20}=10+76 \\ a_{20}=86 \end{gathered}[/tex]

Answer:

86 seats in row 20.