You have $49 to spend in 12 pints of three different types of berries.
Strawberries $3.50/pint
Blackberries $4.00/pint
Raspberries $4.50/pint
You want to buy the same amount of each berry, if the total amount of berries you can buy is 12 pints and you have three types of berries, divide 12 by three to calculate what is the max amount of pints per berry type you can buy:
12/3= 4
Now lets check how much you would spend if you buy 4 pints of each berry:
Strawberries 4* $3.50= $14
Blackberries 4*$4.00= $16
Raspberries 4*$4.50= $18
Add them:
$14+$16+$18= $48
With $49 and considering you want to buy the same amount of each berry type, you can buy 4 pints of each berry