Answer :
Let:
T = Total pictures
U = Pictures they used
[tex]\begin{gathered} T\times0.4=U \\ 0.4T=220 \\ \text{Solve for T:} \\ T=\frac{220}{0.4} \\ T=550 \end{gathered}[/tex]Let:
T = Total pictures
U = Pictures they used
[tex]\begin{gathered} T\times0.4=U \\ 0.4T=220 \\ \text{Solve for T:} \\ T=\frac{220}{0.4} \\ T=550 \end{gathered}[/tex]