Answer:
a = 60
Step-by-step explanation:
90 + 30 = 120
120 - 180 = 60
8 because 25% is 1/4 of how much he has so just multiply 2 by 4
I think that the answer would be 2 if I am right
Notice that if you go forward, the common ratio is 5. Each new term is found by mult. the previous term by 5.
If, on the other hand, you go backwards (terms decreasing), then you divide a term to find what the previous term was.
Here, divide 1 by 5 to find the first term. It's 1/5.
Perfect square is
a²+2ab+b²
so just take the square root of the end ones and add then double to get middle term
A.
m+10=10m, doubled is 20m
nope
B.
m+5=5m, doubled is 10m, yep
C.
m+2√15=fancy thing that won't get to 36m
D.
m+12=12m, doubled is 24m, yep
B and D