pyramid numbers

[grandfatherd]

could someone please enlighten me on the method of answering problems like this one.
A pyramid of bricks consisting of 5 rows, 5bricks followed with 4 then 3 - 2-1 bricks. The 2nd brick on the bottom row as the No. 48 inserted. 5 one No. 5. Onthe next row No. 1 brick as 59 No. 4 as 25. next row the middle one of 3 as 102. The next row 2 bricks the 1st. one as aquestion markthe last one as a total of390. What no. is the question mark? I would like to thank you in anticipation of an answer

[auntflo]

top row 390
2nd row 226; 164
3rd row 124;102;62
4th row 59; 65; 37;25
bottom row 11;48;17;20;5

[grandfatherd]

Thankyou auntflo but it is the method used to get the answer I wuold like
grandfatherd

[auntflo]

sorry!

ok, if i label the squares to make it easier to explain.....

a
b c
d e f
g h i j
k l m n o

you will have already worked out that n = 20

h and i must equal 102

so l (48) and m and m and n (20) must also equal 102

this means m must be 17

from here you can quickly complete the pyramid