In this equation, there are two formulas, so you can isolate one variable and solve. The two accounts have to equal $23,000 (see first equation below). We also know that each amount earns a specified return, which totals $2,060 (see second equation below). Knowing these two formulas we can solve for either variable. In the example below, we isolate to solve for 'y' first. Isolating the variable and plugging it into the other equation, the answer is 'y' equals $22,000. Plugging the $22,000 into the original equation, we solve for 'x,' which equals $1,000.
x + y = 23,000
.08x + .09y = 2,060
x = 23,000 – y
.08(23,000-y) + .09y = 2,060
1,840-.08y + .09y = 2,060
.01y = 220
y=22,000
x + 22,000 = 23,000
x=1,000
