答案:c,30元
设一支铅笔x元,一块橡皮y元,一本日记本z元,有:含备岁
20x+3y+2z=32 (1)
39x+5y+3z=58 (2)
(1)*2 得40x+6y+4z=64 (3)
(3) —(2)得x+y+z=6
所以:5(x+y+z)=30
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30元
设一支铅前镇笔x元,一块橡皮y元,一本日睁芦记本z元,有:慧早粗
20x+3y+2z=32 (1)
39x+5y+3z=58 (2)
(1)*2 得40x+6y+4z=64 (3)
(3) -(2)得x+y+z=6
所以:5(x+y+z)=30
解:设一支铅笔x元,一块橡皮y元,一本日记本指宴z元,
20x+3y+2z=32 (1)
39x+5y+3z=58 (2)
(1)*2 得40x+6y+4z=64 (3)
(3) -(唯谨银2)得晌游x+y+z=6
5(x+y+z)=30
20a+3b+2c=32
39a+5b+3c=58
19a+2b+c=26
c=26-19a-2b
59a+8b+5c=90
5*(26-19a-2b)+59a+8b=90
130-95a+59a-10b+8b=90
40=36a+2b
b=20-18a
c=26-19a-(40-36a)=17a-16
5a+5b+5c=5(a+b+c)=5(a+20-18a+17a-16)=20