How many minutes is it before 12at noon if 90 minutes ago it was four times as m

游客2024-08-18  10

问题 How many minutes is it before 12at noon if 90 minutes ago it was four times as many minutes past 9 a. m. ?

选项

答案 72

解析 (设是中午12点以前x分钟。根据题意可得此方程式:x=4[12×60一(90+x)一9×60]解得X=72)
转载请注明原文地址:https://tihaiku.com/zcyy/3725227.html
最新回复(0)