We will use B for the number of baseball cards and H for the number of hockey cards.
B = 5H
B + H = 840
Use substitution by plugging 5H in for B in the second equation.
5H + H = 840
6H = 840
H = 140
If there are 140 hockey cards, then there are 5*140 = 700 baseball cards.
So the answer is 700.
Hi, you didn't add any picture or attached the info
Use combine like terms the answer is 7r^2-r-1
12*123.9=1486.8
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You're answer would be 3843000 because the number in the hundredths place is 5 so you would round up your answer