In a parking lot there are motorcycles and cars. you count 98 wheels, and your friend counts 30 vehicles. how many cares are there? how many motorcycles?
assign two variables and equations. solve.

Car normally has 4 wheeles
motorcycles normall have 2 wheels

c=cars
m=motorcycles

4c+2m=98
c+m=30

multiply second equation by -2 and add to the original equaiton

-2c-2m=-60
4c+2m=98 +
2c+0m=38

2c=38
divide 2
c=19
sub

c+m=30
19+m=30
m=11

11 motorcycles
19 cars

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