Question by Summer Clouds - Discuss with MathYouLike

Summer Clouds moderators

14/11/2017 at 08:53

Ben and Jerry each have a collection of toy animals. Ben collects only two-legged toy animals and Jerry collects only toy animals with four legs. Jerry has 10 more toy animals than Ben. There are 220 legs in their combined collections. How many toy animals does Jerry have?

List of answers

Nguyễn Đặng Hoàng Phúc 14/11/2017 at 11:45

Put a,b sequence is the number of toy animals Jerry and Ben have:

Deduced:the legs of toy animals Jerry has is 4a;the legs of toy animals Ben has is 2b

We have:\(\left\{{}\begin{matrix}a-b=10\\4a+2b=220\end{matrix}\right.\)\(\Leftrightarrow\left\{{}\begin{matrix}a-b=10\\2a+b=110\end{matrix}\right.\)\(\Rightarrow3a=120\Leftrightarrow a=40\)

So toy animals Jerry has is 40
1234 này 14/11/2017 at 18:22

Put a,b sequence is the number of toy animals Jerry and Ben have:

Deduced:the legs of toy animals Jerry has is 4a;the legs of toy animals Ben has is 2b

We have:{a−b=104a+2b=220{a−b=104a+2b=220⇔{a−b=102a+b=110⇔{a−b=102a+b=110⇒3a=120⇔a=40⇒3a=120⇔a=40

So toy animals Jerry has is 40
Phan Thanh Tinh Coordinator 14/11/2017 at 09:43

Let a, b be the number of toy animals Ben has and Jerry has respectively. We have :

\(\left\{{}\begin{matrix}b-a=10\\2a+4b=220\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}2b-2a=20\\2b+a=110\end{matrix}\right.\)\(\Rightarrow\left\{{}\begin{matrix}3a=90\\b=a+10\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}a=30\\b=40\end{matrix}\right.\)

So, the answer is 40

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