Answer
See below.
Work Step by Step
We evaluate $z$ at the corner points:
$(0,6):z=(0)+10(6)=60$
$(5,6):z=(5)+10(6)=65$
$(5,2):z=(5)+10(2)=25$
$(4,0):z=(4)+10(0)=4$
$(0,3):z=(0)+10(3)=30$
Thus the maximum value is $65$, the minimum value is $4$.
