Parallelogram abcd is a rectangle. what are the slopes of the sides that make this quadrilateral a rectangle? -2 and 1/2 -1/2 and 2 -1/3 and 3 -3 and 1/3

-3 and 1/3 would be the correct answer. Rise/run. If you count, since its on a graph, one of them is 2/6 which reduces down to 1/3 positive slope. Then the other is -3/1 which reduces down to -3 slope.

The answer is b.3x + 15 = 55 - x

x - Jill's present age
y - dad's present age

In 5 years, Dad will be three times as old as his daughter Jill will be then:
y + 5 = 3(x + 5)

The sum of their present ages is 50:
x + y = 50

We have the system of two equations now:
y + 5 = 3(x + 5)
x + y = 50

Let's rearrange the second equation:
If:         x + y = 50     
Then:  y = 50 - x

Now, substitute y from the second equation (y = 50 - x) into the first one:
y + 5 = 3(x + 5)
50 - x + 5 = 3(x + 5)
50 + 5 - x = 3*x + 3*5
55 - x = 3x + 15

Rearrange it a bit:
3x + 15 = 55 - x
Therefore, the correct choice is b.