A brick staircase has a total of 17 steps, with the first step requiring 118 bricks. Each successive step requires 5 less bricks than the prior one. How many bricks are required to build the staircase?

The answer is 1327.

1326 bricks

Step-by-step explanation:

Step 1 will have 118 bricks

Step2 will be 118-5=113 bricks

Step 3 will have 118 - (2*5) = 108 bricks

Step 17 will have 118 - (16*5) = 38 bricks

The number of bricks in first step is given as 118+5 (n-1) where n starts as 1

At any step n, the number of bricks will be 118+5 (n-1)

The sum of the bricks can be found by

Sum=½n (n (1) + n (17))

Since n (1) = 118 bricks and n (17) is 38 bricks

Sum=½*17 (118+38) = 1326 bricks