Nathan deposited 7/9 of his allowance into his savings account. he spent the remaining ammount, or $2.50. how much did nathan deposit into his savings account?

If he deposited 7/9 then he spent 2/9.
See 7/9 + 2/9 = 9/9

then if $2.50 is 2/9 we divide $2.50 by 2
 which makes $1.25 equal to 1/9

1/9 × 7 = 7/9 (amount deposited)

$1.25 × 7 = $8.75

A) for the n row: 22+(n-1)×6therefore,b) 100-22=78that means (n-1)×6=7878÷6=1313+1=1414th row has 100 seats