B5+b3=60 b7-b5=144 надо найти b4

Question

B5+b3=60 b7-b5=144 надо найти b4

Answer 1

7b-5b=144
2b=144
b=72

5b+3b=60
8b=60
b=60
8
b=15
2

Comments

Ой

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Ой b=15

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B=15 в внизу 2