Answer:
A) Check the first two: 2(x+5) and 2(x) + 2(5)
B) Check the last one: 14y + 2
Let x be your first alloy
2/5x+7/10(30-x)=1/2(30)
4x+210-7x=150
3x=60
x=20
So, you need 20 lbs of the first alloy, and 10 parts of the second to make 30 lbs of half iron and half silver alloy!
880, theres no change in between, only after every 13 years
Answer:
y=4x-3
then add 3 to each side to get: y+3=4x.
Next, just divide both sides by 4 to get x = (y+3)\div4.