Help! Each week, Christian earns $x fixing bicycles and receives $10 as his allowance.

To find how much he will earn in total over 2 weeks, Christian calculates : x + 10 + x + 10

What is another way Christian can calculate how much he will earn in total over the 2 weeks?

A: x + 10

B: 2x +10

C: x +20

D: 2(x + 10)