is pretty much the same as the Pablo buying the computers and City charges, so without much fuss let's proceed.
a = invested at 7%
b = invested at 5%
we know she invested a total of 20,000, thus a + b = 2000.
how much is 7% of a? (7/100) * a, 0.07a.
how much is 5% of b? (5/100) * b, or 0.05b
we know the yield is 1060, thus 0.07a + 0.05b = 1060.
[tex]\bf \begin{cases}
a+b=20000\implies \boxed{b}=20000-a\\
0.07a+0.05b=1060\\
----------\\
0.07a+0.05\left( \boxed{20000-a} \right)=1060
\end{cases}
\\\\\\
0.07a+1000-0.05a=1060\implies 0.02a=60
\\\\\\
a=\cfrac{60}{0.02}\implies a=3000[/tex]
how much was invested at 5%? well, b = 20000 - a.