How much money (in dollars) does she have if she has 11 dimes and 12 quarters?: $4.10
How much money in dollars does she have if she has x dimes and y quarters?: 10x+25y=$?
(There are no numbers for the second one so there is no way to determine the amount of money. Therefore, it is an equation.)
Work:
11x10=110
110/100=1.10
25x12= 300
300/100=3
1.10+3=4.10
Hope this helps :)