Write a algebraic equation for the following problem and then solve it.

Shelley decided to invest $13000 of her retirement fund conservatively. She invested part of this money into one account that pays 4% simple interest and part into another account that pays 2% simple interest. Last year she earned $ 420 in interest. How much did she invest in each type of account?

Let x equals the amount invested at 4% interest. Write an expression that is equal to 420 the amount of interest she earned last year, using the variable x.

jQuery20001674592228627274_1505256637054? = 420

I am not clear on the format requested for the answer-thank you