David invested $220 in a savings account that offers a 3% return on the investment. how many years will the value of david's investment will reach at least $400 ?

FV = PV ( 1 + i ) ^t
FV = $400,    PV = $220,   i = 3% = 0.03
400 = 220 * ( 1 + 0.03 ) ^t
( 1 + 0.03 ) ^t = 400 : 220 = 1.818181
t = log ( 1.03 ) 1.81818
t = 20
After 20 years his investment will reach at least $400.

The answer is: y would equal 3 because if you simplify the equation then it would be y= 3x+9 and if you divide 3x and 9 by 3 it would equal 3. y= 3