Daniel brought a total of 39 pens and pencils and he spent a total of $91. If pencils cost two dollars each and pens cost three dollars each how many of each did he buy

26 pencils and 13 pens

Step-by-step explanation:

First, define the variables. Lets say x represents pens and y represents pencils.

Next, make 2 equations with the information provided.

2y+3x=91

y+x=39

Then, multiply the second equation by 2 so a variable (y)  can be canceled out.  

2y+3x=91

2y+2x=78

Subtract the 2 equations

x=13

Next, substitute 13 in for x in the second equation.

y+x=39

y+13=39

Subtract 13 from both sides, and y=26

no i do not : ( what is it?

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