Answer:
A. 5(1 + 3x)
Explanation:
5(1 + 3x)
(5 × 1) + (5 × 3x)
5 + (5 × 3x)
5 + 15x
A works. Let's check the rest.
1(5 + 3x)
(1 × 5) + (1 × 3x)
5 + (1 × 3x)
5 + 3x
B does not work.
3(5 + х)
(3 × 5) + (3 × x)
15 + (3 × x)
15 + 3x
C doesn't work.
5(3x)
5 × 3x
15x
B, C, and D do not work.