Answer: 
Step-by-step explanation:
Let be "x" the time in minutes a 150-pound person must walk at 4 mph to use at least 190 calories.
The amount of calories that a 150-pound person uses in 1 minute when walking at a speed of 4 mph is:

Therefore, knowing this, we can write the following proportion:

Finally, we must solve for "x" in order to find its value.
Multiplying both sides of the equation by 190, we get this result:

Answer: -91
Step-by-step explanation:
13x, x=-7
plug in the -7 to x
13(-7)
multiply
<h3>
-91</h3>
I got the second one done, I️ just need to know the formula for recursive and explicit formula
Answer:
4(5x - 3y)(5x + 3y)
Step-by-step explanation:
Assuming you require the expression factored.
Given
100x² - 36y² ← factor out 4 from each term
= 4(25x² - 9y²) ← is a difference of squares and factors in general as
a² - b² = (a - b)(a + b) , thus
25x² - 9y²
= (5x)² - (3y)² ← with a = 5x and b = 3y
= (5x - 3y)(5x + 3y)
Thus
100x² - 36y² = 4(5x - 3y)(5x + 3y) ← in factored form