17. (a) The formula with CP subject is 
(b) The Cost Price of item without GST is $59.50
(c) The GST of item is $5.95
Step-by-step explanation:
Given formula is;
SP = 1.1 * CP
SP = Selling price
CP = Cost price
(a) Rearrange the formula to make CP the subject;
SP = 1.1 * CP
Dividing both sides by 1.1

The formula with CP subject is 
(b) Use your formula from (a) to find the Cost Price of an item without GST if the selling price is $65.45
SP = $65.45

The Cost Price of item without GST is $59.50
(c) Calculate the amount of GST on an item whose selling price is $65.45.
GST = 10% of CP
GST = 
GST = 0.1CP
From part (b)
CP = $59.50
GST = 0.1 * 59.50
GST = $5.95
The GST of item is $5.95
Keywords: percentage, multiplication
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It opens upward and the vertex is (2,-6) here are some plotted points: (0,6),(1,-3),(2,-6),(3,-3),(4,6). Hope that helps. I hate graphing but if you do it enough times you'll get the hang of it!
Money earned by restaurant on Friday=$1073
Money earned by restaurant on Saturday=$1108
Let Money earned by restaurant on Sunday=$x
Average=$1000

Number of observation=3
⇒ 3× 1000=1073+1108+x
⇒3000= 2 181+x
⇒3000-2181=x
⇒x=819
The restaurant needs to earn on Sunday to average $1000 per day over the three-day period=$819
Loss
gain means you’re getting more, which is positive