Step 3 is wrong . Jorge incorrectly applied the addition and subtraction properties of equality
50 + 5.5f < = 100
5.5f < = 100 - 50
5.5f < = 50
f < = 50/5.5
f < = 9.09....she can invite, at most, 9 friends
Y=mx+b
-b -b
--------------
-by= mx
-------------
m m
-by
------
m
I don't think this is possible...
But if you mean 9 then the root is 3
