NOTE THIS IS AN EXAMPLE:
Let t = time, s = ostrich, and g = giraffe.
Here's what we know:
s = g + 5 (an ostrich is 5 mph faster than a giraffe)
st = 7 (in a certain amount of time, an ostrich runs 7 miles)
gt = 6 (in the same time, a giraffe runs 6 miles)
We have a value for s, so plug it into the first equation:
(g + 5)t = 7
gt = 6
Isolate g so that we can plug that variable value into the equation:
g = 6/t
so that gives us:
(6/t + 5)t = 7
Distribute:
6 + 5t = 7
Subtract 6:
5t = 1
Divide by 5:
t = 1/5 of an hour (or 12 minutes)
Now that we have a value for time, we can plug them into our equations:
1/5 g = 6
multiply by 5:
g = 30 mph
s = 30 + 5
s = 35 mph
Check by imputing into the second equation:
st = 7
35 * 1/5 = 7
7 = 7
