Math Gold Medalist

Lor

2024 AMC 8 

Problem 12

Rohan keeps a total of 90 guppies in 4 fish tanks. There is 1 more guppy in the 2nd tank than the 1st tank. There are 2 more guppies in the 3rd tank than the 2nd tank. There are 3 more guppies in the 4th tank than the 3rd tank. How many guppies are in the 4th tank?

$\textbf{(A)}\ 20 \qquad \textbf{(B)}\ 21 \qquad \textbf{(C)}\ 23 \qquad \textbf{(D)}\ 24 \qquad \textbf{(E)}\ 26$

Translating Word Problems Into Equations

Replacement

a2=a1+1

a3=a2+2

a4=a3+3

a1+a2+a3+a4=90

Find a2, a3, and a4 in terms of a1 and replace in the last equation

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   Solution