If $60\%$ of $x$ is $22$, then what is $45\%$ of $x$?

For this case we are told that 60% of a number "x" is 22. Then, to find the number we make a rule of three:

x --------------> 100%

22 ------------> 60%

Now, we find 45% of the number "x" found:

36.67 --------> 100%

y ---------------> 45%

Where "y" represents the number that is 45% of x.

So, 15.50 is 45% of x

16.50 is 45% of x

he earned 78.75 in interest.

step-by-step explanation: