Concept:Use the rules of signs for addition and subtraction of integers.Explanation:Rewrite the expression by removing brackets.−(−20)=+20 and +(−10)=−10.So, −15−(−20)+(−10)=−15+20−10.Add the positive and negative terms separately.−15−10=−25 and then add +20.Therefore, −25+20=−5.Answer:The simplified value is −5, which is option B.