You can work out the percentage change and that would help you work out the rate of appreciation :)
The formula is ((new value - old value)/old value) * 100.
So you do 
Therefore the rate of appreciation is 8% p/a.
So 45% of 35 is 16.2 so subtract 16.2 from 36 and you get A 19.2
In this question, the speed of the dolphin is already given, but the unit is different. The speed of the dolphin is given as 40 miles per hour and it has to be converted to feet per hour.
We already know that 1 mile = 5280 feet
Then
40 mile = 5280 * 40 feet
= 211200 feet
So the speed in feet per hour will be 211200 feet per hour. I hope the procedure is clear enough for you to understand. You can always use this method for solving similar problems without requiring any help from outside.
X-4y=-12
4x-y=12
eliminate y's
multily 2nd equaiton by -4 and add to top one
x-4y=-12
<u>-16x+4y=-48 +
</u>-15x+0y=-60
-15x=-60
divide both sides by -15
x=4
sub back
x-4y=-12
4-4y=-12
minus 4 both sides
-4y=-16
divide both sides by -4
y=4
x=4
y=4
(x,y)
(4,4)<u>
</u>
the answer is 32 because 32×(1/4) or 32/4 is 8 there for 8 is a fourth of 32
