Question

Marcy has a total of 100 dimes and quarters. If
the total value of the coins is $14.05, how many
quarters does she have?

Answer 1

100 dimes and quarters

so
dimes = x
quarters = y

x + y = 100

we note that a dime is 0.10 cents
and a quarter is 0.25 cents
so

x(0.10) + y(0.25) = 14.05

Thus we have two equations
x + y = 100
x(0.10) + y(0.25) = 14.05

Do you know how to solve for x and y?

Answer 2

umm substitution?

Answer 3

That is easiest.