The profit

The profit made by a business in 2018 was triple that made in 2019. The profit in 2020 was R 3 million less than the profit in 2019. If the total profit in these three years was R 67 million, what was the profit made in 2020?

Correct answer:

c =  11000000

Step-by-step explanation:

$$\begin{gathered} a=3\cdot b \\ c=b-3000000 \\ a+b+c=67000000 \\ a-3b=0 \\ b-c=3000000 \\ a+b+c=67000000 \\ Row3-Row1\to Row3 \\ a-3b=0 \\ b-c=3000000 \\ 4b+c=67000000 \\ Pivot:Row2\leftrightarrow Row3 \\ a-3b=0 \\ 4b+c=67000000 \\ b-c=3000000 \\ Row3-\frac{1}{4}\cdot Row2\to Row3 \\ a-3b=0 \\ 4b+c=67000000 \\ -1.25c=-13750000 \\ c=\frac{-13750000}{-1.25}=11000000 \\ b=\frac{67000000-c}{4}=\frac{67000000-11000000}{4}=14000000 \\ a=0+3b=0+3\cdot 14000000=42000000 \\ a=42000000 \\ b=14000000 \\ c=11000000 \end{gathered}$$

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