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Lucas has 4 fewer one-dollar coins than ten-cent coins. The total value of all the coins $7. How many coins does Lucas have in all?

 Apr 20, 2021
 #1
avatar+290 
+2

4 * $1 = $4

$7 + $4 = $11 (Cost of same number of each

                         type of coins)

$1 + $0.10 = $1.10 (Value of 1 pair)

$11 ÷ $ 1.10 = 10 (pairs)

10 * 2 = 20

20 - 4 = 16

Lucas has 16 coins in all.

 Apr 20, 2021
edited by Tgfromthe4  Apr 20, 2021
 #2
avatar+507 
+1

$100\cdot(x-4)+10\cdot{x}=100x-400+10x=700$

$110x=1100$

$x=10$

$10+(10-4)=\boxed{16}$

 Apr 20, 2021

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