Problem Solving (PS) | Re: If 3^a – 3^(a – 2) = 8(3^27), what is the value of 2a ?

3^a - 3^(a-2) = 8(3^27)
3^a -(3^a/3^2) = 8(3^27)
take lcm = 3^2 and then cross multiply the denominator
(3^a)(3^2) - (3^a) = (3^2)(8)(3^27)
take (3^a) common on LHS
(3^a)[9-1] = (3^29)(8)
cancel 8 on both sides
(3^a) = (3^29)
a= 29
2a = 58
option E

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