Answer:
The British defeat of the Mahdist forces at Omdurman finally brought an end to the shameful and horrific slave trade. This sentence does not maintain a formal style and tone because it uses charged language
Step-by-step explanation:
Writings with a formal style and tone are characterized for the use of impersonal language, and words and phrases that are precise and elegant. This style, then, is devoid of overly subjective opinions and of excessive adjectives that contribute to a charged language. The words “shameful” and “horrific” create a charged and subjective language in the sentence and make it informal.