Respuesta :

evgeniylevi

Answer:

70°

Step-by-step explanation:

1. the rule is: m(∠1)+m(∠2)+m(∠3)=180°.

2. the substitution according to the rule above:

b+2b-90+b-10=180;

4b=280;

b=70°
It’s 70 degrees . I hope that helps if it doesn’t, send me a message

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