Question 1173936
his total investment was 300,000.
let x = the investment in the electronic shop and y equal the investment in real estate.
first equation is x + y = 300,000.
second equation is .15x + .08y = 40,000.
first equation tells you the amount invested.
second equation tells you the interest on the investment.


these two equations need to be solved simultaneously.
they are:
x + y = 300,000
.15x + .08y = 40,000


multiply both sides of the first equation by .15 and leave the second equation as is to get:
.15x + .15y = 45,000
.15x + .08y = 40,000


subtract the second equation from the first to get:
.07y = 5,000
solve for y to get:
y = 5,000 / .07 = 71,428.57143
solve for x to get:
x = 300,000 - 71,428.57143 = 228,571.4286.


replace the two original equations with these values for x and y to get:
x + y = 228,571.4286 + 71,428.57143 = 300,000
.15x + .08y = .15 * 228,571.4286 + .08 * 71,428.57143 = 40,000.
this confirms the solution is correct.
the solution is that he invested 228,571.4286 in the electronics shop.