Write as a single fraction: \(\frac{5}{6r} - \frac{3}{4r}\)

Factorize 2x\(^2\) - 21x + 45

Solve the simultaneous equations y = 3x; 4y - 5x =14

A sector of a circle of radius 9cm subtends angle 120° at the centre of the circle. Find the area of the sector to the nearest cm\(^2\) [Take π = 22/7]

Calculate the total surface area of a cone of height 12cm and base radius 5cm. [Take π = 22/7]