Seems to be an arythmetic sequence
Sn=[n(a1+an)]/2
where
Sn means sum of all terms up the nth term
n=number of terms
a1=first term
an=nth term
so from 86 to the 22th term is from a1 to a22
find teh sequence
miknus 7 each time
an=a1+d(n-1)
an=87-7(n-1)
find 22n term
a22=87-7(22-1)
a22=87-7(21)
a22=87-147
a22=-60
S22=[22(87-60)]/2
S22=[22(27)]/2
S22=594/2
S22=297
the sum is 297
They would each have to pay 1,500 dollars to purchased the house
solve for "y" so it is in the form y = mx + b. "m" is the slope and "b" is the y-intercept.
ax + by = c
by = -ax + c <em>subtracted "ax" from both sides</em>
y = (-a/b)x + c/b <em>divided both sides by "b"</em>
Answer: slope is -a/b and y-intercept is c/b
The cross product of two vectors gives a third vector

that is orthogonal to the first two.

Normalize this vector by dividing it by its norm:

To get another vector orthogonal to the first two, you can just change the sign and use

.
Answer: 7
How many took 7.5 OR less. This means it includes the hikes that took 7.5 hours. Count all of the ones that start from 7.5 and lower