The cost of C (in dollars) of making n watches is represented by C=15n+85. How many watches are made when the cost is $385?
1 answer:
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Answer:
<u>The</u><u> </u><u>requ</u><u>ired</u><u> </u><u>num</u><u>ber</u><u> is</u><u> </u><u>7</u><u>0</u><u>.</u>
Step-by-step explanation:
let the no. be 10y + x where x is unit digit and y is ten's digit.
given , sum of the digit is 7
x + y = 7 ...(1)
also , reversing the no. we get 10x + y ,where x is ten's digit and y is unit digit.
given reversed digit decreases the number by 63 .
so, 10y + x - ( 10x + y ) = 63
9y -9x = 63
( dividing both side by 9 )
y - x = 7 ....(2)
adding 1 and 2 [ refer attachment ]
so the required original number is
10y + x = 10×7+0 = 70
