we know that
triangles BCD and ACE are similar
so, their ratios of sides must be equal
Calculation of y:
we can see that
AC=AB+BC
AC=y+3
CE=CD+DE
CE=4+6
CE=10
now, we can plug values
now, we can solve for y
Calculation of AC:
we know that
AC=y+3
we can plug y
and we get
...................Answer