The cost 5

The cost of three chairs and four tables is 320.00. If two chairs and five of the same kind cost 330.00, find the cost of
(i) 4 chairs
(ii) 3 tables

Correct answer:

x =  160
y =  150

Step-by-step explanation:

$$\begin{gathered} 3a+4b=320 \\ 2a+5b=330 \\ 3\cdot a+4\cdot b=320 \\ 2\cdot a+5\cdot b=330 \\ 3a+4b=320 \\ 2a+5b=330 \\ Row2-\frac{2}{3}\cdot Row1\to Row2 \\ 3a+4b=320 \\ 2.33b=116.67 \\ b=\frac{116.66666667}{2.33333333}=50 \\ a=\frac{320-4b}{3}=\frac{320-4\cdot 50}{3}=40 \\ a=40 \\ b=50 \\ x=4\cdot a=4\cdot 40=160 \end{gathered}$$

$y=3\cdot b=3\cdot 50=150$

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