有18个同学在练球,其中4个同学离开,又来15个同学,现在有多少个同学?/K4?/m;Y5M7t+k0y)D:^3n9`4C5a0A
算式:提示4A.S+G7O;h9B-K8i6s*X/h0M;H/S6u'Z/K4?/m;Y5M7t+k0y)D:^3n9`4C5a0A
答;现在有/A8n4N'B.[2I:A.D4w个同学。/K4?/m;Y5M7t+k0y)D:^3n9`4C5a0A