Based on the information given the couple's back-end DTI is 29.38%.
First step
Borrower 1's annual income=$60,000/ 12 month
Borrower 1's annual income= $5,000
Second step
Total monthly income =$3,000+ $5,000
Total monthly income=$8,000
Third step
Couple's back-end DTI=$1,500+$500+$350/$8,000
Couple's back-end DTI=$2,350/$8,000
Couple's back-end DTI=29.38%
Inconclusion the couple's back-end DTI is 29.38%.
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