See the formula of the present value of annuity ordinary through Google
When you solve for PMT
First plan
PMT=28,000÷((1−(1+0.07083)^(−3))
÷(0.058))=8,750.06
SECOND PLAN
PMT=28,000÷((1−(1+0.07083)^(−3))
÷(0.07083))=10,685.63
So the answer is the second investment