请教一道GWD的数学题

迹部女王

From May 1 to May 30 in the same year, the balance in a checking account increased. What was the balance in the checking account on May 30?

(1)   If, during this period of time, the increase in the balance in the checking account had been 12 percent, then the balance in the account on May 30 would have been $504

(2)   During this period of time, the increase in the balance in the checking account was 8 percent.

答案是C。好像考点就条件一中if的问题，不明白