Part A
If the running back previously gained 7 yards on his carry.
He later loses 7 yards on his carry, he would have gained 0 yards in total.
[tex]\begin{gathered} \text{Gai}n=7\text{ yards} \\ \text{Loss:}-7\text{yards} \\ 7+(-7)=0\text{yards} \end{gathered}[/tex]Part B
You had a debt of $55 in your account.
If there is a deposit of $55 into the account.
The balance of the account will be $0.
[tex]\begin{gathered} \text{Debt: -\$55} \\ \text{Deposit: \$55} \\ \text{Balance: -55+55=\$0} \end{gathered}[/tex]