This is a price-demand function question for business calculus The price-demand equation for gasoline is 0.4d + 2p = 70. Where p is the price per gallon in dollars and d is the daily demand measured in millions of gallons. Write the demand d as a function of price. What would the demand be if it were $6 per gallon

This should be put as a comment, but you shouldn't be struggling much with this. This question has a simple solution in which you substitute 6 into $p$.

$0.4d+2(6)=70$

$0.4d = 58$

I cannot give you more than this.

And if you're asking for the demand as a "function of price", isolate the variable d.

**NOTE: $1/5 = 0.2$ and $2/5=0.4$**

$2p = 70-2/5d$

$p = 35-1/5d$

MULTIPLY BY 5 ON BOTH SIDES.

$5p = 175-d$

$d=-5p+175$

If you want to know the "demand d as a function of price", it would be

$f(p)=-5p+175$