(1) a=b=±3
1/2÷2/a×b/8=9/32
1/2×a/2×b/8=9/32
ab/32=9/32
ab=9
a=b=±3
(2)a=3
a/8÷b/7÷21/32=1
a/8×7/b×32/21=1
4a=3b
∵b=4
∴a=3