math
posted by Nicole .
For her vacation Mrs. Andrews bought $300 worth of traveler's checks in $10 and $20 denominations. If she has 22 travelers checks in all, how many of each denomination does she have?
Let x represent the number of $10 traveler's checks she has. Which expression represents the value of the $20 traveler's checks she has?

number of 10's  x
number of 20's  22x
10x + 20(22x) = 300
10x + 440  20x = 300
10x = 140
x = 14
She bought 14 10's and 8 20's
check: 14+8 = 22 check!
10(14) + 20(8) = 300 check!
BTW, time to update that textbook, I wonder how many people under 30 would even know what a traveler's check is.