单选题 How many hours were budgeted for a certain job?(1)The number of hours budgeted for the job plus the actual number of hours used for the job was 140.(2) The actual number of hours used for the job minus the number of hour budgeted for the job was 8.
【正确答案】 C
【答案解析】假设The number of hours budgeted for the job为x,the actual number of hours used for the job为y,那么得到:单独(1)x+y=140,一个方程两个未知数有无数解;单独(2)y-x=8,一个方程两个未知数有无数解;把(1)和(2)结合起来考虑,两个未知数,两个方程,可以求解,所以答案为C。