Quantitative Aptitude - Arithmetic Ability Questions

The reciprocal of the sum of the reciprocals of 2/9 and 7/10 is

Raghuram sells a machine for Rs 43 lakhs at a loss. Had he sold it for Rs 53 lakh, his gain would have been 7 times the former loss. Find the cost price of the machine.

The age of Rakhi is twelve times that of her daughter Anubha. If age of Anubha is 3 years now, then what was the age of Rakhi, 2 years earlier?

Present age of A is 2 times the present age of B. After 8 years the B's age will be 4 times of C's present age. If C celebrated his fifth birthday 9 years
ago, then what is the present age (in years) of A?

10 identical solid spherical balls of radius 3 cm are melted to form a single sphere. In this process 20% of solid is wasted. What is the radius (in cm) of the bigger sphere?

What is the value of sin ­7π/4c?

The Simplified form of (b3x2a4z3)*(b4x3a3z2)/(a2b4z3) is

If sin3A = x, then value of x is