Answer:
The principal he borrowed is $1500
Explanation:
Let's assume principal he borrowed as P
now, we can use formula
![SI=(P* r* t)/(100)](https://img.qammunity.org/2020/formulas/mathematics/middle-school/koywq9rf422kg17jkisnbaopsfuamhzl1z.png)
where
SI is simple interest
r is interest rate
t is time in years
we are given
r=4%
SI=240
t=4
now, we can plug this value
![240=(P* 4* 4)/(100)](https://img.qammunity.org/2020/formulas/mathematics/middle-school/t09huzjd9vsf043rh1egu389xqw35v207v.png)
now, we can solve for P
![16P=24000](https://img.qammunity.org/2020/formulas/mathematics/middle-school/uj3gxa70rxf0wwi292i1qysgf4mujd2s8d.png)
![P=1500](https://img.qammunity.org/2020/formulas/mathematics/middle-school/uovx3qqer2fp82v094ceohridxxie5aydc.png)
So,
The principal he borrowed is $1500