The area of a square field is A square feet and the perimeter is p feet. If 6A=6(2p+9), what is the perimeter of the field, in feet? (Here A=a^2) Select
A) 28	B) 36	C) 40	D) 56	E) 84

Rationale: you can also solve this via using the given numbers in the answer choices ! of course you need to be aware of the basic properties as outlined by the other posts above ( a = x ^ 2 and p = 4 x ) starting with d you will notice that x = 14 is way too big for your area ( 14 ^ 2 ) and will not satisfy : 6 a = 6 ( 2 p + 9 ) or a = 2 p + 9 - - > eliminate d and e now pick b ( its either too big , then its a , or too small then you know its c or it is b itsself ) and picking b indeed solves the problem ! ( 36 / 4 - - > 9 ; a = 9 ^ 2 = 81 and 81 = 2 x 36 + 9 )
Answer: B