Alan found 4 marbles to add to the 5 marbles in his collection. Then, he went to the store and tripled the number of marbles he had.

27 Marbles

Step-by-step explanation:

Alan first had 5 marbles, and then added 4 to the collection.

5 + 4 = 9    

He went to the store and tripled the number of marbles he had.

9 x 3 = 27

Hence, he now has 27 marbles.                                            

x =-.20752

step-by-step explanation:

4^(x+2)=12

4^(x+2)=12

take the log base 4 on each side

log 4 (4^(x+2) = log 4(12)

we know log b(a^y) = y log b (a)

(x+2) log 4(4) = log 4 (12)

x+2 = log 4 (12)

we know   logb c = loga c/loga b

we want to convert to base 10   so a = 10

by default, we do not write the 10   c = 4   and b = 10

log4 10 = log 12/log 4

log4 10 = log 12/ log 4

x+2 = log 12/ log 4

subtract 2 from each side

x +2 -2 = log 12/ log 4 -2

x = 1.79248125 -2

x =-.20752