use what they tell you to create the equations
a=33+2b & 57=3b-a
for this to work we need to substitute a variable to get rid of it.
look at
57=3b-a (lets switch it around s that the equation reads "a=")
57+a=3b
a=3b-57 (this is our new equations)
so now we know that
a=33+2b & a=3b-57
so we can write 33+2b=3b-57. we have now "gotten rid" of "a"
SOLVE FOR B
33+2b=3b-57 (get variable alone)
33= 3b-2b-57 (subtract and add accordingly)
33= b-57
33+57=b
90=b (this means that movie b is 90 long)
SOLVE FOR A
you can plug "b" into any of the original equations.
a=33+2b
a=33+2(90)
a=33+180
a=213
CHECK
plug "a" into any of the original equations to find "b" if b=90 then you know you've done it right
213=33+2b
213-33=2b
180=2b
180/2=b
90=b
hope this helps :)
