Can someone help me understand this by showing stepsexplanat

Can someone help me understand this by showing steps/explanation

Solution

Total invested = 30000 $
Rates of 5,6 and 7%

So, let
x$ be invested at 5%
y$ at 6%
z$ at 7%

We have
x + y + z = 30000

x$ at 5% will get interest of 0.05x
Similarly for y and z tooo....

So, 0.05x + 0.06y + 0.07z = 1700

y + z = 200 + x

So, using these :
x + y + z = 30000
0.05x + 0.06y + 0.07z = 1700
y + z = 200 + x

We can solve...

x = 14900
y = 10200
z = 4900