Simplify \( \frac{1}{p} - \frac{1}{q} + \frac{p}{q} - \frac{q}{p} \)

A man earns ₦3,500 per month out of which he spends 15% on his children's education. If he spends additional ₦1,950 on food, how much does he have left?

If P is a set of all prime factors of 30 and Q is a set of all factors of 18 less than 10, find \(P \cap Q\)

Convert 726 to a number in base three

If log3x2 = -8, what is x?

If \(27^{x+2} \div 9^{x+1} = 3^{2x}\), find x

Simplify \( (\sqrt{6}+2)^2-(\sqrt{6}-2)^2 \)

Evaluate \( \frac{21}{9} \) to 3 significant figures

Simply \( \frac{2\frac{2}{3}\times1\frac{1}{2}}{4\frac{4}{5}} \)