The amount he invested in the account that yields 4.5% interest is $7,500.
The amount he invested in the account that yields 2.5% interest is $12,500.
a + b = $20,000 equation 1
0.045a + 0.025b = $750 equation 2
Where:
a = amount he invested in the account that yields 4.5% interest
b = amount he invested in the account that yields 2.5% interest
Multiply equation 1 by 0.025
0.025a + 0.025b = 500 equation 3
Subtract equation 3 from 2
250 = 0.02a
a = 12,500
Subtract 12,500 from 20,000
20,000 - 12,500 = $7,500
To learn more about simultaneous equations, please check: https://brainly.com/question/25875552