Shannon had five times the number of metallic blocks as Archie. Shannon used all her blocks to build 8 identical planes. Archie used all his blocks to build 4 identical planes. Shannon used 9 more blocks than Archie for each plane. How many blocks did Archie have?

	Shannon	Archie
Number	8	4
Value	1 u + 9	1 u
Total value	8 u + 72	4 u

Number of metallic blocks that Archie used for each plane = 1 u
Number of metallic blocks that Shannon used for each plane = 1 u + 9

Number of metallic blocks that Archie had
= 4 x 1 u
= 4 u

Number of metallic blocks that Shannon had
= 8 x (1 u + 9)
= 8 u + 72

Shannon had five times the number of metallic blocks as Archie.

5 x 4 u = 8 u + 72
20 u = 8 u + 72
20 u - 8 u = 72
12 u = 72

1 u = 72 ÷ 12 = 6

Number of blocks that Archie had
= 4 u
= 4 x 6
= 24

Answer(s): 24