Answer:
She have 5 number of dimes and 7 number of nickel
Explanation:
let
number of dimes = a
number of nickels = b
Total number of dimes and nickel can be expressed as follows:
a + b = 12 ..........(i)
Total cost of dimes and nickel can be express below:
1 dimes = 10 cents
1 nickel = 5 cents
10a + 5b = 85...........(ii)
combine the equation
a + b = 12 ..........(i)
10a + 5b = 85...........(ii)
a = 12 - b
insert the value of a in equation (ii)
10(12 - b) + 5b = 85
120 - 10b + 5b = 85
120 - 5b = 85
120 - 85 = 5b
35 = 5b
divide both sides by 5
b = 35/5
b = 7
Insert the value of b in equation (i)
a + b = 12 ..........(i)
a + 7 = 12
a = 12 - 7
a = 5
She have 5 number of dimes and 7 number of nickel