14. (a) Without using tables, evaluate:- 2 tan 53° cot 37° − cot 80° tan 10°   15. (b) Given that x ∈ R, solve the following inequality and graph the solution on the number line: −1 ≤ 3 + 4x < 23   16. (c) Find the mean of the following distribution:- Class interval 20 - 30 30 - 40 40 - 50 50 - 60 60 - 70 70 - 80 Frequency 10 6 8 12 5 9