A、rECtAngulAr Floor 18 FEEt By 10 FEEt is to BEComE plEtEly CovErED with CArpEting thAt Costs x DollArs pEr squArE yArD、in tErms oF x，how mAny DollArs will thE CArpEting Cost (1 yArD=3 FEEt)
A、20xB、28x
C、60x
D、180xE、540x