Mary’s dad is 3 years less than double her age. the difference in their age is 31.

Mary is 34 years old, and Dad is 34 + 31, or 65, years old.

Step-by-step explanation:

Represent the ages of Dad and Mary by d and m respectively.

Write and solve a system of linear equations as follows:

d = 2m - 3

d - m = 31

Substituting 2m - 3 for d in the second equation, we get:

2m - 3 - m = 31

Combining like terms results in

m = 34.  Mary is 34 years old, and Dad is 34 + 31, or 65, years old.

c. y = 1/4 x + 5

step-by-step explanation:

first, put the equation of the line on the graph into slope-intercept form

(y = mx + b):   y = -4x + 8

second, a perpendicular line has to have "an opposite/reciprocal slope" to the original slope. so, find the "m" value in your original equation (it's -4, right? )

original slope: m = -4   perpendicular slope: change the sign to its opposite and find the reciprocal ("flip" the number)

new slope is now positive (b/c the original slope was negative 4), and it's 1/4 (not the original slope of 4 or 4/1)