You would use the same process as shown in the example.
Notice how each digit of a base 5 number is multiplied by 5^x (where x is the digit's place in the whole number).
So here is how you would convert 310 from base 5 to base 10.
[tex]3 \times 5 ^{2} + 1 \times {5}^{1} + 0 \times {5}^{0} [/tex]
^ that becomes:
[tex]75 + 5 + 0[/tex]
Your answer would be: 80
