We are given
The average income, I, in dollars is

(a)
now, we are given
average income is $275000
so, 
now, we can set them equal
and then we can solve for x


we will have to use quadratic formula


we get


we need to find youngest age
It means that we need to choose smallest value
so,
............Answer
(b)
we are given
x=40
so, we can plug it and find I

..............Answer
Answer:

Step-by-step explanation:
Answer:
b² = a² + c² - 2ac cos B
Step-by-step explanation:
The cosine rule can be use when you are given three sides of a triangle and ask to find any angle or when you are given two sides and a included angles(the angle between the two sides given) and ask to find the length of a side.
The equation Sophia can use to solve for the side length(b) of a triangle when given two length and the included angle can be expressed below. Sophia was given two sides and an included angle and was asked to find a side length b.
For sides a, b and c the cosine rule can be represented below
a² = b² + c² - 2bc cos A
b² = a² + c² - 2ac cos B
c² = a² + b² - 2ab cos C
The equation required base on your question is
b² = a² + c² - 2ac cos B
Answer:

Step-by-step explanation:
the third option