As you can see there are two triangles but it can be done calculating just for one. First we must understand how formula for area of triangle works.

Where
represents base (hypotenuse) and
as height of the triangle.
We know that:

Using this data we fill the formula.

Hope this helps.
r3t40
Given that t<span>here
are 20 light bulbs in 5 packages.
The table to find the rate
that gives you the number of light bulbs in 3 packages is given as follows:
![\begin{tabular} {|c|c|c|c|c|c|} Light bulbs&4&8&12&16&20\\[1ex] Packages&1&2&3&4&5 \end{tabular}](https://tex.z-dn.net/?f=%5Cbegin%7Btabular%7D%0A%7B%7Cc%7Cc%7Cc%7Cc%7Cc%7Cc%7C%7D%0ALight%20bulbs%264%268%2612%2616%2620%5C%5C%5B1ex%5D%0APackages%261%262%263%264%265%0A%5Cend%7Btabular%7D)
Three different ways in which the rate can be written are:
12 light bulbs to 3 packages
12 light bulbs : 3 packages
12 light bulbs / 3 packages
</span>
(0,4)(2,-3)
slope = (-3 - 4) / (2 - 0) = -7/2