Kilograms of fruit

Mom paid SKK 132.50 for the purchase. She bought bread, 5 kg apples, and three liters of milk. We know that bread costs twice as much as milk, and a kilogram of apples costs 6.50 SKK less than milk. How many SKKs did milk and bread and a kilogram of apples cost?

Correct answer:

a =  30.4 SKK
b =  15.2 SKK
c =  8.7 SKK

Step-by-step explanation:

$$\begin{gathered} a+5b+3c=132.50 \\ a=2b \\ c=b-6.5 \\ a+5\cdot \frac{a}{2}+3\cdot (a/2-6.50)=132.50 \\ a+5\cdot a/2+3\cdot (a/2-6.50)=132.50 \\ 10a=304 \\ a=\frac{304}{10}=30.4 \\ a=\frac{152}{5}=30.4=\frac{152}{5}\text{SKK}=30.4\text{SKK} \end{gathered}$$

$b=a/2=30.4/2=\frac{76}{5}\text{SKK}=15.2\text{SKK}$

$c=b-6.5=15.2-6.5=\frac{87}{10}\text{SKK}=8.7\text{SKK}$

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