2 years ago

PLS HELP ASAP ILL GIVE 10 points PLSS

2 answers:

8 0

The twins are 13
I did it by seeing that 89 ended in 9
So I figured the triplets ages had to end in 3 when all combined.
I tried different things and then eventually got 21 x 3 = 63 and 89 - 63 = 26 lastly 26/2=13
Let me know if that was right :)

umka21 [38]2 years ago

5 0

Answer:

The twins would be 13 years old.

Step-by-step explanation:

21+21+21+13+13 = 89

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Determine the sum of the arithmetic series: 5+18 +31 +44 + ... 161.

Finger [1]

Answer:

1079

Step-by-step explanation:

Hello,

18-5 = 13

31-18=13

44-31=13

161=5+13*12

So we need to compute

$\displaystyle \sum_{k=0}^{k=12} \ {(5+13k)}\\\\=\sum_{k=0}^{k=12} \ {(5)} + 13\sum_{k=1}^{k=12} \ {(k)}\\\\=13*5+13*\dfrac{12*13}{2}\\\\=65+13*13*6\\\\=65+1014\\\\=1079$