2x+3y=60 solve for x...
x=(60-3y)/2
p=xy^3, using x from above:
p=y^3(60-3y)/2
p=(60y^3-3y^4)/2
dp/dy=(180y^2-12y^3)/2
dp/dy=90y^2-6y^2
dp/dy=0 when:
90y^2-6y^3=0
6y^2(15-y)=0, we know y>0 so
y=15, since x=(60-3y)/2
x=7.5
(We solved it this way because otherwise you get quartic equations and cubic derivatives, yuck :P)
Some points are (7,3) and (-7,-5).
Well convert 3 5/6 to 23/6 and 4 4/5 to 24/ 5
then find a multiple that both 5 and 6 have which is 30
23x5= 115 and 24x6= 144
so 115 x 144= 16560/30
16560/30 = 552 /1 so your answer is
552
