It is possible to do many simple tricks with numbers. Here is one trick. It has seven steps.
First, write down your house number. For example, if your address is 73 Lemon Street, you would write down 73.
Next, double it. In other words, multiply(乘) it by two. Then, add five to this doubled number. For example, if your address was 73 and you doubled it, you would get 146. Then, if you added five, you’d get 151.
So, to repeat the first three steps, write down your house number, double it, and add five.
Fourth, multiply this number by 50. In our example here, if you multiply 151 by 50, you’ll get 7550.
The fifth step is to add your age to this total. For example, if you’re 26 years old, you should add 26 to this total. In our example here, the result would be 7550 plus 26, you’ll get 7576.
Sixth, you have to add the number of days in a year, which is 365. In our example here, 365 added to 7576 is 7941.  
The seventh and final step is this: subtract(减) 615 from the number that you have. In our example, 7941 minus 615 is 7326.
The result here, 7-3-2-6, is the trick. The first part of the number is the address and the last part of the number is the age of the person. That is, 73 is the address that we started with, and 26 is the age that we used.
If you follow these seven steps with any address and the age of any person. You will get the same result.
73 According to the trick, what number can you get if you are 16 years old and your house number is 85？
A. 1685          B. 8516          C. 8165          D. 1658
74. How can your age number appear at the last part of the result?
A. It’s really a trick.
B. By taking all the steps except Step1 and Step 2.
C. By taking Step 6 and Step 7.
D. By taking all the steps.
75. What’s the secret of the trick?
A. It’s impossible to know.
B. By taking Step 2 and Step 4, we get the formula(公式)：your address number ×2×50.
C. By taking all the steps except 1 and 2, we get the formula: 5×50+your age number+365－615="your" age number.
D. Both B and C.