Answer:

Step-by-step explanation:
Given


Required
Represent as an equation;

Expand the above

<em>Recall that b = $10 ----given</em>
 becomes
 becomes


 
        
             
        
        
        
The student added 9 1/2 instead of adding -9 1/2
        
             
        
        
        
Answer:
7
Step-by-step explanation:
An easy way to find any percentage of a number is to multiply with decimals. To do this you have to first convert the percentage to a decimal. Do this by moving the decimal point in the percentage 2 places to the left. This means that 2.0% becomes 0.02. Then, multiply this decimal by the whole number. So, 0.02*350. This equals 7, which is 2% of 350.
This same trick will work with any problem. For example 38% of 435 is the same as 0.38*435, which equals 165.3.