Question 79468
X*Y=27 X=27/Y
2X+2Y=21
2(27/Y)+2Y=21
54/Y+2Y=21
(54+2Y^2)/Y=21 CROSS MULTIPLY
54+2Y^2=21Y
2Y^2-21Y+54=0
(2Y-9)(Y-6)=0
2Y-9=0
2Y=9
Y=9/2
Y=4.5 ANSWER.
Y-6=0
Y=6 ANSWER.
PROOF
6*4.5=27
27=27
2*4.5+2*6=21
9+12=21
21=21