5 and 1/4 can be 5.25 so all you have to do is divide that by 3 and you’ll get 1.75 per container.
If you wanted to keep it as a fraction, 5 and 1/4 would become 21/4 (you do 5 x 4= 20 + 1) and for fractions I always remembered dividing as ‘Keep, Change, Flip’ so you would do 21/4 for keep. Change would be to change the sign from division to multiplication. And for Flip you would flip 3 over 1 (3/1) to 1/3
Putting that all together would be 21/4 x 1/3 which also equals 21/12 by multiplying the denominators and numerators. Then you simplify, dividing it by 3 to equal 7/4 and another simplify to be 1 and 3/4 which is 1.75.
Hope this helps!