Mr.Harris has some money in his wallet. He pays the babysitter $12 an hour for 4 hours of babysitting. His wife gives him $10, and he puts the money in his wallet. By how much does the amount in his wallet change??
Ok. So since we do not know the total he starts with, we can use a variable.
x is his first amount.
Then he pays the babysitter 12 dollars an hr for 4 hours.
12*4 = 48
so x-48
x-48
Now, his wife gives him $10
-48+10 = -38
The amount in his wallet changes by -38. Therefore, he loses 38 dollars.
How much went out ?
(12 x 4) = $48.
How much went in ?
$10 .
The change = 48 out + 10 in = 38 less.