If he took x trips last year
3x+1=7
3x=6
x=2
he took 2 trips last year
1, 3, 5, 7, 9 ......
notice, there are consecutive odd integers, every other number
skip one, another, skip one, another and so on
so, from 1 to 3, is 1 + 2 =3
5 is 3 +2
7 is 5+2
and so on
let us pick an odd integer, hmmm say "a"
to find the next odd one, it'd be "a + 2" of course :)
we know their sum is 316
so

once you found "a", the next one is, well, "a + 2" :)
Answer:
-4 or 5
Step-by-step explanation:
let number be x
x²-x=20
Rearrange
x²-x-20=0
(x+4)(x-5)=0
Separate
x+4=0, x-5=0
x=-4 or 5
Answer to A:
50%
Explanation for A:
We're looking for how many numbers are odd, so theres 1, 3, 5 ,7, four numbers.
We have a total of 8 numbers.

To make any number a percent we move the point over to the right by two, which makes our final answer 50%
Answer to B:
37.5%
Explanation for B:
If the number is less than four, that means we need to find if it will roll the first three numbers. We, once again, have eight total possibilities

0.375 can be turned into our final answer, 37.5%
Answer:
Midpoint coordinates are 
Step-by-step explanation:
The Coordinates of R = (-8,3)
The Coordinates of S = (9, -7)
Let M be the mid point of M and its coordinates by (x,y)
Now, by mid point formula,

⇒
So, the midpoint coordinates are 