Question 306785
Let x=amount invested at 5%
Let y=amount invested at 7%


Equation 1: x+y=4000
Equation 2: 0.05x + 0.07y=230


Isolate for y in Eqn. 1 and substitute it into Eqn 2:


y=4000-x


Put this value of y into Eqn 2 instead of y:


0.05x+0.07(4000-x) = 230
0.05x +280-0.07x = 230
-0.02x = -50
x=2500


Plug this value of x into Eqn 1 to solve for y:


x+y=4000
y=4000-x
y=4000-2500
y=1500


So $2500 was invested at 5%, and $1500 was invested at 7%.