Question 161472
Moolah has 27 coins that are all dimes and quarters. The value of th coins is $4.35. How many dimes and how many quarters does Moolah have?
---------------------
D + Q = 27   (a total of 27 coins)
10D + 25Q = 435 (each dime is 10 cents, each quarter 25 cents.  See that?)
-------------
Now it's 2 eqns in 2 variables, no longer a "word problem"
Substitution is the easiest approach.
Since D + Q = 27, D = 27-Q.
Sub for D in the 2nd eqn
10*(27-Q) + 25Q = 435
270 - 10Q + 25Q = 435
270 + 15Q = 435
15Q = 165
Q = 11  (11 quarters)
D = 27-Q
D = 16
That's it.