-9-4d=3+8b first combine like terms so add 4b on both sides so its
-9=3+12b next subtract three on both sides
-12=12b next divide 12 on both sides
-1=b
Year 1
$12500 x .07 = $875
12500-875=11625
Year 2
11625 x .07 = $813.75
11625-813.75=10811
Year 3
10811 x .07 = $756.79
10811-756.79= 10054.21
Year 4
10054.21 x .07= 703.79
10054.21-703.79= 9350.42
So after 4 years expect to get $9350.42
Start with parenthesis first.
so a+a+2a+48
Then add all like terms.
4a=48
Then solve for a by dividing 4 from 48.
a=12
