There are 23 sharks and 7 octopi in the aquarium
If the total number of animals in the tank is 30, therefore;
If the total number of legs in the tank is 171 with starfish having 5 legs and Octopus having 8 legs, the required expression will be:
From equation 1, x = 30 - y ................... 3
Substitute equation 3 into 2 to have:
5(30-y) + 8y = 171
150 - 5y + 8y = 171
3y = 171 - 150
3y = 21
y = 7
Recall that x = 30 - y
x = 30 - 7
x = 23
Hence there are 23 sharks and 7 octopi in the aquarium
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