-----------------------------------------
Define x :
-----------------------------------------
Let x be the number of 5 cents she has.
5 cents = x
10 cents = 2x
-----------------------------------------
Find value in term of x :
-----------------------------------------
5 cents = $0.05x
10 cents = 0.10(2x) = 0.2x
-----------------------------------------
Construct Equation :
-----------------------------------------
The total amount is $3.50
⇒ 0.05x + 0.2x = 3.50
-----------------------------------------
Solve x :
-----------------------------------------
0.05x + 0.2x = 3.50
0.25x = 3.5
x = 14
-----------------------------------------
Find the number of coins :
-----------------------------------------
5 cents = x = 14
10 cents = 2x = 2(14) = 28
-----------------------------------------
Answer: She has 14 5-cents.
-----------------------------------------
