I don't think you're stupid. ^^
Let's take the third term, 8. If n=3, then an should be 8.
The first answer gives 15+2.5*3=22.5.
The second answer gives 15.5+2.5=23.
The third answer gives 15-2.5*3=7.5.
The fourth answer gives 15.5-2.5*3=8.
Choice 4 is correct.
Let's try to actually find the equation on our own.
The equation for an arithmetic series is an=a0+dn where a0 is the term that comes before the first term.
The first term given is 13 and it decreases by 2.5 each time so n=-2.5 and the term that would be before 13 is 15.5.
Thus the equation is an=15.5-2.5n
The answer is $160. You have to subtract 200 from 20%
Answer:
Last one
Step-by-step explanation:
Imagine it as a mirror or like a paper folding in half, then figure out the direction it shifts.
Answer:

Step-by-step explanation:
we know that
The formula to calculate the coordinates of the midpoint between two points is equal to

we have that
The coordinates of hk

substitute in the formula to calculate the midpoint



The answer is A
B and D are not answer as they show50-x=50
so x have to be 15 or 5 in A and C
but in C x=5 but 2×x+50 is nt equal to 70
so it is A