Substitution.
Here is an example.
Let x be equal to 3 and y equal to 3.

From this we can conclude that the values of both x and y are equal to three therefore x and y have the same value and are equal.

Here in your case we have:

Hope this helps.
r3t40
Answer:
a) 75 miles
b) 90 minutes
c) His constant speed was higher for a longer period of time
Step-by-step explanation:
a) 70 / 2 = 35
40 + 35 = 75
b) 60 + 30 = 90
Answer:
-1
Step-by-step explanation:
-7/10+7/15+1/-20+-9/10+11/15+11/-20
= -7/10 + -9/10 + 7/15 + 11/15 + 1/-20 + 11/-20
= -16/10 + 18/15 + 12/-20
= -8/5 + 6/5 + -3/5
= (-8+6-3)/5
= -5/5
= -1
The answer is 3f
<span>=<span><span>18f</span>+<span>−<span>15f</span></span></span></span><span>=<span>(<span><span>18f</span>+<span>−<span>15f</span></span></span>)</span></span><span>=<span>3<span>f</span></span></span>