Ella simplifies open paren 3 b plus 4 r close paren plus open paren negative 2 b minus r close paren and says the result is b plus 5 r What error did Ella make?

Combine like terms: the b terms give 3b + (−2b) = b, and the r terms give 4r + (−r) = 3r. The correct result is b + 3r, so Ella incorrectly combined the r coefficients and got 5r instead.

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