If that little dot after the '1' is a comma, then you're correct. Melting doesn't change the mass.
Answer:
w + r 》 4 (greater than/equal to 4)
270w + 650r 》 1500
I think the answer would be 4/5
First, you need to distribute the right side of the equation : 8n - 2
Now the equation is : 20 - 7n = 8n - 2
Add 2 to both sides : 22 - 7n = 8n
Add 7n to both sides : 22 = 15n
Divide both sides by 15 : ( I had to round this one) 1.5 = n
