Since the dimensions of the length and width are equal, then the board and the picture are squares. The width of the board is the margin surrounding the picture. Let's denote the width to be x. The length of the picture plus the length of the width at both ends should equal the length of the board. So, the equation should be:
10 1/2 in = 8 3/4 + 2x
Solving for x
x = 7/8 inches
Answer:
Part 1) 
Part 2) 
Step-by-step explanation:
Part 1)
we know that
The equation of the line in slope intercept form is equal to

we have

Isolate the variable y
subtract 2x both sides

Divide by B both sides

Part 2)
we know that
The equation of the line in slope intercept form is equal to

we have

Isolate the variable y
subtract 2x both sides

Divide by 8 both sides

Simplify

First, we get the z-score using formula:
z =( X - μ ) / σ
From the problem, we substitute the given values:
z = (9 - 7.8) / 1.7
z = 0.71
From the z-table (one-tailed), for a z-score of 0.7059, the proportion of numbers that are greater than 9 is 0.76.
X^4 / x = x^3 so the answer cant be A or B
Must be C