# Tim and Mary are building a special brick wall in the town playground. There will be 212 bricks in the bottom layer, 204 bricks in the second layer, 196 bricks in the third layer, and so on in the same pattern. The wall will be 20 layers high. They want to know how many bricks will be in the top layer. • Drag and drop a response into the first box that represents the explicit expression that can be used to find out how many bricks will be in the top layer. • Drag and drop the number of bricks that will be in the top layer into the second box a = n The number of bricks in the top layer is ____ Responses: 212+(n-1)(8) 212+ (n-1)(-8) 212+(8-1)(n) 212+(8-1)(-n) 60 72 352 364

So, to determine the number of bricks in the top layer, the explicit expression we can use is aₙ = 212 + (n - 1)(-8). It is known that there are 60 bricks in the top layer. To solve an arithmetic progression problem, we need to use the formula for the nth term, which is aₙ = a + (n - 1)d. In this case, a represents the first term, n represents the position of the term, and d represents the common difference. Given the sequence of bricks as 212, 204, 196,..... we can derive the values of a and d, which are 212 and -8 respectively. Therefore, the formula to express this arithmetic sequence is aₙ = 212 + (n - 1)(-8). To find the number of bricks in the 20th layer, we can substitute n = 20 in the formula, which gives us a₂₀ = 212 + (20 - 1)(-8) = 60. For more information on arithmetic progression, please visit brainly.com/question/6561461 #SPJ1.