Maths questions series #4

If $$ \sqrt{0.04×0.4×a} =0.4×0.04×{\sqrt{b}}$$ then the value of $$ {a\over b}$$ is:

If $$  3 ^{2x-y}=3^{x+y}=\sqrt{27}$$ then the value of y is

A scooter was purchased for Rs 30,000 and Rs 3,000 was spent to repair it. It was sold for Rs 39,600. What was the profit percentage?

If a vendor sells apples at Rs 170 per kg he suffers 15 % loss. If he sells at Rs 230 per kg, then what is his profit percentage? 

An alloy contains copper and tin in the ratio 3: 2. If 250 gm of copper is added to this alloy then copper in it becomes double the quantity of tin in it. What is the amount (in gm) of tin in the alloy? 

In what proportion must a grocer mix sugar at Rs. 12 a kg and Rs. 7 a   kg Sugar as to make a mixture worth Rs 8. a kg?

A man borrowed some money from a private organisation at 5 % simple interest per annum. He landed this money to another person at 10% compound interest per annum, and made a profit of Rs. 26,410 in 4 years. The man borrowed