To find an average you take the numbers to be averaged and add them together then You take the number and divide it by the number of numbers, in this case 4, and that gives you the average.
on this problem you want to do the opposite. you know the average she wants, an 87, so you multiply it by 4. 87*4=348. then you add the three numbers you have (88,81 and 87) and you get 256.
then you subtract 256 from 348 and you get 92. 92 is your answer to check just add 87+81+88+92=348
348/4=87
87 was the average she wanted.
Hope this helped! good luck :)
Answer:
360°
Step-by-step explanation:
Sum of exterior angle of any polygon = 360
Sum of exterior angle of pentagon = 360
Formula for compound interest is
Interest = Amount - Principal
Interest = 
- P
Where r = rate in percent
t = time in years
For Jaina,
P = $300
r= 7%
t = 3 yrs
So, Interest = 
- 300
For Tomas
P = $400
r= 4%
t = 3 yrs
So, Interest = 
- 400
So pair of equations for Jaina and Tomas are
Interest = - 300
Interest = - 400
