The telephone bill of a certain establishment is party fixed and partly varies as the number of calls consumed. When in a certain month 540 calls made the bill is Rs.1800. In another month 620 calls are consumed then the bill becomes Rs.2040. In another month 500 units are consumed due to more
holidays. The bill for that month would be :  Choose the correct choice from the following:	A) Rs.1560	B) Rs.1680	C) Rs.1840	D) Rs.1950	E) Rs.1690
Let the fixed amount be Rs. X and the cost of each unit be Rs. Y.   Then, 540y + x = 1800 …. And 620y + x = 2040   On subtracting (i) from (ii), we get 80y = 240 -&gt; y = 3   Putting y = 3 in (i) we get :   540 * 3 + x = 1800 x = (1800-1620)= 
<gadget id="calculator">(1800-1620)</gadget>
<output>180</output>
180   . : Fixed charges= Rs.180, Charge per unit = Rs.3.   Total charges for consuming 500 units = 180 +(500*3) = Rs.1680   Answer:Rs.1680
<result>B</result>
The telephone bill of a certain establishment is party fixed and partly varies as the number of calls consumed. When in a certain month 540 calls made the bill is Rs.1800. In another month 620 calls are consumed then the bill becomes Rs.2040. In another month 500 units are consumed due to more
holidays. The bill for that month would be :