Question 918208
x+y=150,
80*x+60*y=10000
x=150-y
80*(150-y)+60*y=10000
12000-80y+60*y=10000
-20*y=-2000
y=100
x=150-y
x=50 rooms at $80 ($4000)  and  y=100 rooms at $60 ($6000) 
check
50+100=150
80*x+60*y=10000
80*50+60*100=10000
4000+6000=10000
10000=10000
ok
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