Since you subtract 6 and you have to find the sixth term, you can do: -6×5=-30 ( negative shows you're subtracting and since 75 is the first term, then you have to find the difference of the input/term 6-1, the sixth term minus the first) 75-30=45 You can check by actually continuing the pattern. 75,69,63,57,51,45,39......
If the 26 bricks are each 7 cm, seems like multiplication or repeated addition would solve the problem. Multiplication would be faster. 26 x 7 = 182 182 cm tall.
