Given:
4/5 of a pie left after their family picnic.
Each slice of pie was 1/15 of the total pie.
To find:
The number of remaining slices of pie.
Solution:
Let x be the number of remaining slices of pie.
Part of total pie in one slice = [tex]\dfrac{1}{15}[/tex]
Remaining part of total pie in x slices = [tex]\dfrac{1}{15}x[/tex]
According to the question, 4/5 of a pie left after their family picnic.
[tex]\dfrac{1}{15}x=\dfrac{4}{5}[/tex]
Using cross multiplication, we get
[tex]5\times x=15\times 4[/tex]
[tex]5x=60[/tex]
Divide both sides by 5.
[tex]x=12[/tex]
Therefore, the remaining number of slices of pie is 12.