For the following questions answer them individually
The total cost of 8 buckets and 5 mugs is 92 and the total cost of 5 buckets and 8 mugs is 77. Find the cost of 2 mugs and 3 buckets.
If $$\frac{a}{1-a} + \frac{b}{1-b} + \frac{c}{1-c} = 1$$ the the value of $$\frac{1}{1-a} + \frac{1}{1-b} + \frac{1}{1-c}$$
If $$(x-3)^2 + (y - 5)^2 + (z-4)^2 = 0$$ then the value of $$\frac{x^2}{9} + \frac{y^2}{25} + \frac{z^2}{16}$$
What number must be added to the expression $$16a^2 -12a$$ to make it a perfect square ?