A server earned 55 €in tips, all in 1€ and 2€ coins. She had 38 coins all together. How many 2€ were there? 💶💶
Let n1 = number of 1-Euro coins and n2 = number of 2-Euro coins
1*n1 + 2*n2 = 55 (1)
n1 + n2 = 38 (2)
Subtract (2) from (1) term by term
0 + n2 = 55 - 38
n2 = 17
Using (2)
n1 + 17 = 38
n1 = 21
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