After Becca's half-marathon, her pedometer showed 23, 580 steps, while Alex recorded
2.42 x 104 steps after the same race. What is the combined amount of their steps?
A
4.778 x 103 ; 4,778
B
2.3822 x 104 ; 23,822
C
4.778 x 104 ; 47, 780
D
4.808 x 104 ; 48,080