smc-902-60-Rates and cost

Number, NAP-L3-CA30 SA

Petrol costs 158.5 cents per litre.

How much does 12 litres of petrol cost?

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`$19.02`

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`text(1 litre costs $1.585)`

`:.\ text(12 litres cost)`	`= 12 xx 1.585`
	`= 19.02`

Damon buys 25 kilograms of salt for his pool for $33.75.

The salt can be purchased in 1 kilogram bags.

How much does 9 kilograms of salt cost?

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`$12.15`

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`text(C)text(ost of 1 kilogram)`

`= 33.75/25`

`= $1.35`

`:.\ text(C)text(ost of 9 kilograms)`

`= 9 xx 1.35`

`= $12.15`

John's old tractor used 8.3 litres of fuel per 100km.

His new tractor uses 5.9 litres of fuel per 100 km.

John pays $1.35 per litre and drives 20,000 km each year.

How much money will John save on fuel each year with his new tractor?

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`$648`

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`text(Fuel cost of old tractor)`

`=8.3 xx $1.35 xx (20\ 000)/100`

`=8.3 xx $1.35 xx 200`

`=$2241`

`text(Fuel cost of new tractor)`

`=5.9 xx $1.35 xx (20\ 000)/100`

`=5.9 xx $1.35 xx 200`

`=$1593`

`:.\ text(John’s fuel savings each year)`

`=2241 – 1593`

`=$648`