After securing a $280,000 settlement from a copyright infringement case, acclaimed author Adrian decided to distribute his unexpected windfall into three distinct investment vehicles: fixed-term savings account yielding 4%, a treasury note yielding 5%, and some high-grade corporate bonds yielding 7%. Following one fiscal year, his investment portfolio yielded an impressive $15,400 in earned interest. 

Determine the amount Adrian invested in each instrument, given that he allocated $20,000 more into the high-grade corporate bonds than he did in the treasury note. Utilize your preferred method of solving systems of equations to find the solution.