Question 141263
How do I solve uing two equations in two variable? 
A shipment of TV sets, some weighing 30kg each and the others weighing 50 kg each, has a total weight of 880 kg. If there are 20 sets all together, how many weigh 50 kg? 
I got the first equation of: 880=30t+50k, but can't figure out the second equation.
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Let # of 30kg sets be t
Let # of 50 kg sets be k
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EQuATIONS:
Quantity Equation: t + k = 20
Weight Equation  :30t+50k = 880
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Rearrange:
3t + 5k = 88
t = 20-k
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Substitute to solve for K:
3(20-k) + 5k = 88
60 -3k + 5k = 88
2k = 28
k = 14 (# of 50 kg sets(
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Substitute into t = 20-k to solve for "t":
t = 20 -14 = 6 (# of 30 kg sets)
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Cheers,
Stan H.