Answer:
N+F=42 & F+3N=70 System Solved: Natalie is 14 and Fred is 28
Step-by-step explanation:
Using variables N=natalies age and F=Freds age
N+F=42 ----> N=42-F (take this and plug it into the other equation)
F+3N=70 so F+3(42-F)=70 [simplify] F+126-3F=70 [further simplify]
-2F=-56 [divide -56 by -2] F=28 [then plug this number into the orig. equation]
So N+28=42 or N=14.
Answer:
Penny would need to put in ~ $18,181.82
Step-by-step explanation:
Using the equation 
Where A = the total
P is equal to the starting amount
r is equal to the rate (percent)
and t is equal to the total time.
We can put in:
A = $40,000
r = 0.08 (8%)
t = 15

Round to the nearest whole cent
P = $18,181.82
Always to do each to 1 sigfig 20-6=14
Answer:
83.4% or 83%
Step-by-step explanation:
when trying to find a percent, divide the numerator (# of correct answers) by the denominator (# of total questions possible to get correct)
Which would be 16.67 divided by 20 which equals .8335. Move the decimal point over two placements which would be 83.35. I rounded it up to 83.4. If trying to find a whole number not a decimal it would be 84%. Depending on the grading scale, it would be a B.