The first one (top left) is a function. Use the vertical line test, if a vertical line crosses the line drawn on the graph twice, then it's not a function.
Since 3 neckties will be out from the
store, so you need to know how much is the cost of 3 ties.
$59.99 x 3 = $179.97 and divide it by two
because the costumer will only pay for 2
$179.97 / 2 = $89.99 is the new price
Mark up = 89.99 – 59.99 = $30.00
% mark up = [(89.99/59.99) -1] * 100
= 50%
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