22. 向量a→\overrightarrow{a}a,b→\overrightarrow{b}b,c→\overrightarrow{c}c满足2a→+b→=(0,−5,10)2\overrightarrow{a}+\overrightarrow{b}=(0,-5,10)2a+b=(0,−5,10),c→=(1,−2,−2)\overrightarrow{c}=(1,-2,-2)c=(1,−2,−2),且a→⋅c→=4\overrightarrow{a}\cdot \overrightarrow{c}=4a⋅c=4,则b→⋅c→=(\overrightarrow{b}\cdot \overrightarrow{c}=(b⋅c=( )))