Susan 2

Susan packed some sugar into small and large packets. The total mass of 4 large packets and three small packets is 43 kg. Each large packet is 2kg heavier than each small packet. What is the mass of a large packet of sugar?

Correct answer:

a =  7 kg

Step-by-step explanation:

$$\begin{gathered} 4a+3b=43 \\ a=2+b \\ 4\cdot a+3\cdot b=43 \\ a=2+b \\ 4a+3b=43 \\ a-b=2 \\ Row2-\frac{1}{4}\cdot Row1\to Row2 \\ 4a+3b=43 \\ -1.75b=-8.75 \\ b=\frac{-8.75}{-1.75}=5 \\ a=\frac{43-3b}{4}=\frac{43-3\cdot 5}{4}=7 \\ a=7 \\ b=5 \end{gathered}$$

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