using pythagoras' theorem:
a² + b² = c²
reverse i: b² = c² - a²
a=9 and c= 15
b² = 15² - 9²
b² = 144
b =12
The number of sales Bob needs to make to get $6000 salary this month's is, 70000. The option B is the correct option.
What is percentage ?
Percentage of a number is the part of the number expressed in the in every hundred. Percentage of a number is expressed with the symbol '%'.
The annual salary of Bob is $30,000. As, there is total 12 months in a year. Thus, the monthly salary of Bob is,

Thus, the monthly salary of Bob is $2500.
The commission on the sale is 5% on all sales he makes, and the Bob wants to make $6,000 this month. Thus, the number of sales he needs to make is,

The number of sales Bob needs to make to get $6000 salary this month's is, 70000. The option B is the correct option.
Learn more about the percentage here;
brainly.com/question/24304697
Just Distribute the squared to both g and a

When Distributing an exponent outside the parenthesis you multiply the exponents
Which results in...

It would be: 5/17 * 3/8 = 5*3 / 17*8 = 15/136
In short, Your Answer would be 15/136
Hope this helps!