She worked as a carpenter for 12 hours and as a blacksmith for 18 hours.
Assuming you mean she earned $20 as a carpenter and $25 as a blacksmith per hour, with a total of 30 hours for $690,
let c represent carpenter hours and b for blacksmith hours.
20c + 25b = 690
c + b = 30
Subtract b from each side so that c = 30 - b
Plug this value into the first equation
20(30 - b) + 25b = 690
600 - 20b + 25b = 690
600 + 5b = 690
5b = 90
b = 18
To find c, plug this value of b into the other equation
c + 18 = 30
c = 12
Answer:
x = (y+w)/k
Step-by-step explanation:
xk-w=y
Add w to each side
xk-w+w=y+w
xk = y+w
Divide each side by k
xk/k = (y+w)/k
x = (y+w)/k
It is not. In the decimal system each column to the right is valued at powers of ten starting at zero and increasing as you move to the left...in a four digit number...the columns are valued at...
10^3, 10^2, 10^1, 10^0 which corresponds to...
1000, 1000, 10, 1 in this case the first digit is equal to
5(1000)=5000 the value of the last digit is 5(1)=5
So the first 5 is 1000 times as great as the second 5...
Hope this helps!
