Construct your variables in this manner: Let x represent the amount of money invested into mutual funds. Let y represent the amount of money invested into bonds. What do you know about $x+y$? (hint: it is given in the question).
Next, construct your other linear equation: Use the second part of the information given to you. In particular, the interest earned by x and y can be represented as a coefficient in front of x and y. How should you arrange the equation to show that the amount of interest from x is double the amount of interest from y? (hint: what can do you to y in order to have an equality occur?)
Once these equations have been constructed, it is simple to solve for x and y!