1. keith bought 6 baseball cards. his dog ate half of his collection and he was left with 36 cards. how many did he start with?

2. sara spent half of her allowance going to the movies. she washed her family car and earned $7. what is her weekly allowance if she ends up with $13?

1. Answer=66cards

Lets use the variable 'x' to represent the number of baseball cards in Keith's collection that he started with. The following equation can be made.

(x+6)/2=36
multiply both sides by 2
x+6=72
subtract 6 from both sides
x=66 cards

2. Answer=$12

Lets use the variable 'a' to represent Sara's allowance. The following equation can be made:

(a/2)+7=13
subtract 7 from both sides
a/2=6
multiply both sides by 2
a=$12