SOLUTION: 3a-b=5 a=3/4b the answer is (3,4) and i don't understand why

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Question 567770: 3a-b=5
a=3/4b
the answer is (3,4) and i don't understand why
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!
3a-b=5 Start with the first equation


3%28%283%2F4%29b%29-b=5 Plug in a=%283%2F4%29b. In other words, replace 'a' with %283%2F4%29b


%289%2F4%29b-b=5 Multiply


%285%2F4%29b=5 Combine like terms


5b=5%2A4 Multiply both sides by 4.


5b=20 Multiply


b=20%2F5 Divide both sides by 5 to isolate b.


b=4 Divide


Now that we know that b = 4, we can use this to find 'a'

a=%283%2F4%29b Move onto the second equation


a=%283%2F4%29%284%29 Plug in b = 4 (ie replace b with 4)


a=12%2F4 Multiply


a=3 Reduce


So the solutions are a = 3 and b = 4 giving us the ordered pair (3, 4)