Question 1032788
 Mary invested an amount of 20000 partly

x+y=20000

x at the rate of 5% and 

y  at the rate of 8% interest per annum.

If the amount of interest in the second case is 820$ more than the amount of interest earned in the first case,
8%y = 5%x+820
multiply by 100
8y=5x+82000
8y-5x=82000


x+y=100000---------------------(1)
8y-5x=82000-------------------(2)

13y=182000
y=14,000 at 8%


Multiply (1) by 5 and add to (2)
5x+5y=100000
8y-5x=82000

13y=182000
y=14,000

$14,000  invested at 5%?