calculate ph of 0.225M triethylamine chloride. HOW DO I START?

Triethylamine, (CH₃CH₂)₃N, is a weak base. You have to find its dissociation constant Kb first.
It is found that Kb for (CH₃CH₂)₃N is 5.6 × 10⁻⁴.
You may find some other values from other sources. Don't worry, Kb is always given in the question.

(CH₃CH₂)₃N(aq) + H₂O(l) ⇌ (CH₃CH₂)₃NH⁺(aq) + OH⁻(aq) ...... Kb = 5.6 × 10⁻⁴

Initial concentrations :
[(CH₃CH₂)₃N]ₒ = 0.225 M
[(CH₃CH₂)₃NH⁺]ₒ = [OH⁻]ₒ = 0 M

Equilibrium concentrations :
[(CH₃CH₂)₃N] = (0.225 - y) M
[(CH₃CH₂)₃NH⁺] = [OH⁻] = y M

Kb = [(CH₃CH₂)₃NH⁺] [OH⁻] / [(CH₃CH₂)₃N]
y² / (0.225 - y) = 5.6 × 10⁻⁴
y² + (5.6 × 10⁻⁴)y - (1.26 × 10⁻⁴) = 0

Solve the above quadratic equation, and reject the negative y.
y = 0.0109
[OH⁻] = 0.0109 M

pOH = -log[OH⁻] = -log(0.0109) = 1.96
pH = 14.00 - pOH = 14.00 - 1.96 = 12.04

(If different Kb is used, the answer will slightly differ from 12.04.)