The person has to divide the money into 3 parts. Call them x (savings account), y (CD), and z (bonds).
Equation 1: x + y + z = 10000 (because this is all the money he started off with)
Equation 2: 0.02x + 0.03y + 0.04z = 260 (this is the interest that you’d get at the end of year 1 if Equation 3 is satisfied)
Equation 3: x = 2y (he puts twice as much money in the savings account as in the CDs ie if he puts y amount in CDs he’d have to put 2y in savings account)
So basically you have:
x + y + z = 10000
2x + 3y + 4z = 26000
x - 2y + 0z = 0
or more simply
2y + y + z = 10000
4y + 3y + z = 26000
Solve and you shall have your answer.