Answer
$(x-5)^2+(y-5)^2=25$
Work Step by Step
RECALL:
The standard form of a circle whose center is at $(h, k)$ and radius $r$ is $(x-h)^2+(y-k)^2=r^2$.
The circle has a radius of 5 units so $r=5$.
The circle is in Quadrant I and is tangent to both the x and y axes.
With a radius of $5$, then the center is 5 units above the x-axis (y=5) and 5 units to the right of the y-axis (x=5).
Thus, the center is at $(5, 5)$.
With center at $(5, 5)$ and $r=5$, the standard form of the circle' equation is:
$(x-5)^2+(y-5)^2=5^2
\\(x-5)^2+(y-5)^2=25$