Answer:
48 hours
Step-by-step explanation:
Given that,
number of hours Jacob takes to create an app = 24 hours
number of hours both takes to create an app = 16 hours
To find,
number of hour Jacob's friend takes to create an app = x hours
Jacob create 1/24 part of app in an hour
Jacob's friend create 1/x part of app in an hour
Take reciprocal
24x / (x + 24) = 16
24x = 16 (x +24)
24x = 16x + 384
24x - 16x = 384
8x = 384
x = 384/8
x = 48