Ralph spent $72 for 320 baseball cards. There were 40 "old-timer" cards. He spent twice as much for each "old-timer" card as for each of the other cards. How much money did Ralph spend for all the 40 "old-timer" cards?

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Answer 1 · 2018-06-29T19:46:51

See a solution process below:

First, let's call the cost of a "regular" card: #c#

Now, we can call the cost of an "old-timer" card: #2c# because the cost is twice what the other cards cost.

We know Ralph bought 40 "old-timer" cards, therefore he bought:

#320 - 40 = 280# "regular" cards.

And knowing he spent $72 we can write this equation and solve for #c#:

#(40 xx 2c) + (280 xx c) = $72#

#80c + 280c = $72#

#(80 + 280)c = $72#

#360c = $72#

#(360c)/color(red)(360) = ($72)/color(red)(360)#

#(color(red)(cancel(color(black)(360)))c)/cancel(color(red)(360)) = $0.20#

#c = $0.20#

Therefore, Ralph spend #40 xx 2 xx $0.20 = 80 xx $0.20 = $16.00# on the 40 "old-timers" cards