Answer: 45 miles in one hour
Step-by-step explanation:
Answer: 
<u>Step-by-step explanation:</u>
EQ1: x + y = 12 --> x = 12 - y
EQ2: xy = 15
Substitute x = 12-y into EQ2 to solve for y:
(12 - y)y = 15
12y - y² = 15
0 = y² - 12y + 15
↓ ↓ ↓
a=1 b= -12 c=15

Now, let's solve for x:

Lastly, find x² + y² :



Okay, just break it up so you're not overwhelming yourself or anything :)
So here, do it in steps-
Let's do 5(3 + t) first:
Distribute the 5, or in non-mathematical terms, just multiply 5 by 3 and t. This will give you 15 + 5t.
Now onto -3(t + 1):
Again, just multiply -3 by t and 1. This will come out to: -3t - 3.
*Note: the 3 is negative because it's "MINUS 3" in the original equation and remember that any number times a negative, if it isn't negative itself, will turn out to be negative.... (aka "-" x "-" = "+" | "+" x "+" = "+" | "-" x "+" = "-")*
ANYWAY
Now just put both answer together and you get:
15 + 5t -3t - 3. You can only add and minus the LIKETERMS (which are the things that are the same) - in this case, the liketerms are 15 and -3 ,,,, AND 5t and -3t.
15 - 3 = 12
5t - 3t = 2t
12 + 2t is your final answer. Hope that helps! :)
1. 6, 12, 18
2. 8,16,24
3. 12, 24, 36
4. 15, 30, 45, 60
4. 30, 60, 90
15/20 and 16/20
4/5 or 16/20 is greater