20 didn't do it for this one.
"3 miles below sea level" may be written as -3. The negative indicates you are below sea level. Going above sea level means the value would be positive.
"earning 45 dollars" can be written as +45 or simply 45. If you lost 45 dollars, then it would be -45. If you are in debt 45 dollars, then it would be -45.
"moving back 5 spaces" is represented by -5 whereas moving forward 5 spaces is +5 or simply 5.
Answer:

Step-by-step explanation:
To solve this type of problems first need to review some laws of exponents:
When you are multiplying the same base, you need to add the exponents.

When you are raising a base with power to another power, you should keep the base and multiply the exponents:

Now for the expression 
Write the multiplying factors:

Multiply the term 

Then multiply the term 

Simplify the exponents:

Add like terms:

Answer:
The selling price would be Rs 52.5
Step-by-step explanation:
Rs 50 is the actual cost and the 5% profit will amount to Rs 2.5 (50*5%) so total total sales price would be Rs 52.5( Rs 50 + Rs 2.5)
Another way to calculate is (Rs 50 * 1.05) = 52.5