A:10*25+(x-10)*5
B:(10*25+x*5)*90%
A=B
则:10*25+(x-10)*5=(10*25+x*5)*90%
250+5X-50=225+4.5x
200+5x=225+4.5x
5X-4.5X=225-200
0.5x=25
X=50
A:10*25+(x-10)*5
B:(10*25+x*5)*90%
A=B
则:10*25+(x-10)*5=(10*25+x*5)*90%
250+5X-50=225+4.5x
200+5x=225+4.5x
5X-4.5X=225-200
0.5x=25
X=50