Let B=amount invested in bonds, so the investment in money market is 5000-B.
Interest from bonds is 0.06B and in money market is 0.075(5000-B).
Total interest=337.50=0.06B+0.075(5000-B)=375+0.06B-0.075B=375-0.015B.
Therefore 0.015B=375-337.50=37.50, and B=37.50/0.015=37500/15=2500.
$2500 was invested in bonds.
CHECK: 2500@6%+2500@7.5%=150+187.50=$337.50.
If the list given is the choice of answers, then it doesn’t make sense!