16. Higher Order Thinking A cell phone plan is shown at the
right. The rates, which include an unlimited data plan, are the
same each month for 7 months. The total cost for all 7 months
Is $180.39. Let m represent the average number of minutes that
exceeds 700 minutes each month.
a. Write an equation to represent the given situation.
b. Solve the equation to determine how many additional
minutes, on average, you use each month.

45.3592

step-by-step explanation:

94

step-by-step explanation:

average the numbers and use a variable to figure out the minimum to get a 90.

(79+94+91+92+x)/5=90

x = 94

the surface area is 124cm²

step-by-step explanation:

length: 4cm

width: 9cm

height:   2cm

(b) 240

step-by-step explanation:

first, we use the pythagorean formula using the given side lengths to find x. then we use x to find the side lengths. then we add the side lengths to find the perimeter.

pythagorean theorem formula:

a^2 + b^2 = c^2

(x - 20)^2 + (x - 40)^2 = x^2

x^2 - 40x + 400 + x^2 - 80x + 1600 = x^2

x^2 -120x + 2000 = 0

(x - 100)(x - 20) = 0

x - 100 = 0 or x - 20 = 0

x = 100 or x = 20

we see that the solution x = 20 must be discarded because it will give a negative side length and a side length of 0. the only valid solution is x = 100.

perimeter = sum of the lengths of the sides

perimeter = x + x - 20 + x - 40

perimeter = 3x - 60

replace x with 100.

perimeter = 3(100) - 60

perimeter = 300 - 60

perimeter = 240