(12*15-144)/(15+3)
=(180-144)/18
=36/18
=2(题)
12-2=10(题)
设小红做对x题,则小红做错(12-x)题.
15x-(12-x)*3=144
x=10
12-x=12-10=2
答:小红做对10题,则小红做错2题.
(12*15-144)/(15+3)
=(180-144)/18
=36/18
=2(题)
12-2=10(题)
设小红做对x题,则小红做错(12-x)题.
15x-(12-x)*3=144
x=10
12-x=12-10=2
答:小红做对10题,则小红做错2题.