you go to a game show and the prze at the end is a case full of $10 and $20
bills. The hosts tells you there are 400 bills in the case totaling $6,250. To
win you have to figure out how many 10 and 20 $ bills are in the case.
This can be solved with or without using algebra. I'll do it both ways:
1. Without algebra:
If all 400 bills were tens, there would be only $4000, which would be
$2250 short, so 225 of the bills must be worth an extra $10 to make it
worth $6250. So there nust be 225 twenties and the rest (175) tens.
2. With algebra:
Let x = the number of tens and y = the number of twenties
x + y = 400 <-- the bill equation
10x + 20y = 6250 <-- the money equation
Solve that by substitution and get x=175 tens, y = 225 twenties.
Edwin