Question

2^(а) · 2^(а +1) : 2^(2а -1)

Answer 1

$2^{a} * 2^{a +1} : 2^{2a -1}=2^{a+(a+1)-(2a-1)}=2^{a+a+1-2a+1}=2^{2}=2*2=4$