How to do mixture word
like: a restaurant sells large and small sub sandwiches. rolls for the sandwiches are ordered from a baker. the roll for a large sandwich costs $0.25 and the roll for a small sandwich costs $0.15. melissa, the manager of the restaurant, ordered 130 more large rolls than small rolls. what was the greatest number of large rolls she received if she spent less than $63?

So you know that $0.25*130=$32.50 which is under $63 dollars, because there is exactly 130 more large rolls after this we must add the same amount of large rolls as we do small rolls as there is already a difference of 130, after this try trial and error or you work it out like this...
$0.25 x 130 = $32.5
$63 - $32.50 = $30.50
Because there is exactly 130 more which we have already counted then there will be an equal number of small and large rolls therefore you can total the cost for one of each bread roll...
$0.25 + $0.15=  $0.40
We have $30.50 left to buy an equal amount of small and large rolls, so now we simply divide this by the cost of the rolls,
$30.50 ÷ $0.40 = 76 (combination of large and small)
Because you need to work out the number of just the large rolls we now need to calculate the following...
76 ÷ $0.25 = 305
Now add the 305 to the 130 from before (305 + 130 = 435) 

*Not sure if this is correct but if I was given this problem I would work it out like this, if anyone else knows please correct me, I could be using the wrong method*