Arnold and Danny are two twin brothers that are celebrating their birthday. The product of their ages today is smaller by 9 from the product of their ages a year from today. What is their age today?  Choose the correct choice from the following choices:
A) 2.
B) 4.
C) 5.
D) 7
E) 9.
ad = (a+1) (d+1) -9   0= a+d-8   a+d = 8   a=d (as they are twin brothers)   a=d=4   4. is the answer
<result>B</result>
Arnold and Danny are two twin brothers that are celebrating their birthday. The product of their ages today is smaller by 9 from the product of their ages a year from today. What is their age today?