Answer:
If x varies directly as y, then x=ky. y=5 and x=2.5 are substituted into x=ky to find k.
2.5=5k
k=2.5/5
k=5.
K =5 is substituted in x=ky to find y where x is 10.
x=5y
10=5y
y=10/2
y=2
Answer:
tons of high steel and
tons of low steel
Step-by-step explanation:
Let x be the number of tons of high grade steel and y be the number of tons ow low grade steel needed.
In x tons of high grade steel there are
tons of iron
tons of magnese
In y tons of low grade steel there are
tons of iron
tons of magnese
NASA orders 500 tons of steel, so

and specifies that it must be in the proportion 80% iron and 20% magnese, so

From the first equation,

Substitute it into the second equation:

Answer:
9
Step-by-step explanation:
I believe you meant the equal signs to be division symbols haha. The next step would be 18/6.