21. A small factory that produces only upholstered chairs and sofas uses 1 cushion for each chair and 4 cushions for each sofa. If the factory used a total of 300 cushions on the furniture it produced last week, how many sofas did it produce last week ?
(1) Last week the factory produced more chairs than sofas.
(2) Last week the factory produced a total of 150 chairs and sofas.
X-Chairs- 1 cushion for each chair
Y- sofas- 4 cushion for each sofas
Stem: X + 4Y =300
(1) Nothing definite. Insuff.
( 2) X + Y= 150
Using both, X=150 -y + 4y =300
Therefore B is correct : in first case u can have multiple answeres like ..
52 sofa's and 92 chairs , 50 sofas and 1oo charis and still satisfying ... the condition,
but in second case if u fix the "SUM" of both chairs and the sofas then the constraint only gives ONE unique solution that satisfies both the equation....