Answer:
It is 5 units.
Explanation:
We see in the picture that we can create a right triangle where we do a^2+b^2=c^2, or in other words, the b unit is 4 units to the right, and up three, and 4 and three are a and b...
confusing/bad explanation, but 4^2+3^2=c^2
25=c^2
c=5