Andrea is designing the seating arrangement for a concert in her local park. to give everyone a good view, each row must have 4 more seats than the row before it, and the first row can only have 10 seats. andrea plan the rest of the seating by solving for how many seats are in row 20. then explain to andrea how to create an equation to predict the number of seats in any row. show your work, and use complete sentences.

To find the number of seats in the 20th row, we use the arithmetic sequence formula, with first term (a) = 10, common difference (d) = 4 and number = 20.
Tn = a + (n - 1)d
T20 = 10 + 4(20 - 1) = 10 + 4(19) = 10 + 76 = 86
The will be 86 seats in the 20th row.

To find the number of seats in any row, we use
Tn = 10 + 4(n - 1) = 10 + 4n - 4 = 6 + 4n
Tn = 6 + 4n.

Step-by-step explanation:

Let's say x is the amount of $2.70/lb coffee and y is the amount of $3.20/lb coffee.

The total amount is:

x + y = 400

The total worth is:

2.70x + 3.20y = 3.00×400

2.7x + 3.2y = 1200

Solving the system of equations through substitution:

x = 400 - y

2.7 (400 - y) + 3.2y = 1200

1080 - 2.7y + 3.2y = 1200

0.5y = 120

y = 240

x = 160

The grocer uses 160 pounds of the $2.70/lb coffee and 240 pounds of the $3.20/lb coffee.