Devon has been saving $5 & $10 for the past four years. Over spring break he wanted to see how much money he has saved up. After counting the money he calculated that he has a total of $395 & had 49 bills. Based on this information, how many $5 & $10 bills does he have?

19 five dollar bills

30 ten dollar bills

Step-by-step explanation:

x=number of $5 bills

y=number of $10 bills

x+y=49

x=49-y

5x+10y=395

substitute for x

5(49-y)+10y=395

245-5y+10y=395

245+5y-245=395-245

5y=150

5y/5=150/5

y=30

x=49-30=19

The answer is in the image 

The total nom of  code that can be used is equal to 5+3 = 8

For every 8 cars there are 7 trucks

Therefore,

Cars:Truck=8:7

Answer is B)8:7

y=2x+15

where y=Value of coin

x=Age in years

Value of coin after 19 years=2*19+15

=$53

Therefore, Value after 19 years=$53

The answer is in the image 

F=ma

where F=force

m=mass

a=acceleration

Here,

F=4300

a=3.3m/s2

m=F/a

    =4300/3.3

    =1303.03kg

Approximately it is aqual to 1300kg

The answer is in the image 

The solution is given in the image below

Speed=Distance/time

Here,

distance=15m

time=1sec

speed=15/1=15m/sec

Distance=Speed*time

time=15min=15*60sec=900sec

Distance travelled in 15 min=15*900=13,500m

=13500/1000 km=13.5Km