Eric had 300 more lollipops than Richard at first. After Richard had eaten 120 of her lollipops, Eric had thrice as many lollipops as Richard. How many lollipops did Eric have at first?
Let the number of lollipops that Richard started with ==R
Then, the number og lollipops that Eric started with ==R + 300
[R + 300] ==3 [R - 120], solve for R
R ==330 - lollipops that Richard started with.
330 + 300 ==630 - lollipops that Eric started with.