Robert bought one 4.5-lb bag of dog food for $3.89, a 7.5-lb bag of cat food for $6.69, and two 2.3-lb bags of birdseed for $1.89 each. how much did he pay for the animal food?

step-by-step explanation:

the original amount doesn't ''re just looking for the time it takes for 1/2 of the substance to we have

(1/2) =)     take the ln   of both sides

ln (1/2)   = )   and we can write

ln(1/2) = ) lne     and lne   = 1     so we have

ln(1/2) = -.1092t     divide both sides by -.1092

t = ln(1/2)/-.1092 = about 6.347 days = about 6.3 days (rounded)