数学题:合并同类项,快快!
1.x-f+5x-4f
2.2a+3b+6a+9b-8a+12b
3.3pq+7pq+4pq+pq
4.30ab+2bc-15ab-4bc
5.7xy-8wx+5xy-12xy
快快,要详细过程!
还有:3b-3a+1+a-2b
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