The lengths of the sides of a triangle are 15m, 21m, and 28cm. What is the size of the angle facing the side 21m (correct to one decimal place)?

Two fair coins are tossed at the same time. what is the probability of getting a head?

Given that the universal set U={14,15,16,17,18,19,20}, J ={16,19,20} and K= {14,15,18}, find (J' ∩ K')1.

Evaluate 1.25 × 10\(^2\) × 0.125 × 10\(^3\) × 12.5 × 10\(^{-4}\) leaving your answer in standard form