How many quarts of a 50% solution of acid must be added to 20 quarts of a 20% solution of acid to obtain a mixture containing a 40% solution of acid?

x=40

Step-by-step explanation:

0.50x + 20(0.20) = 0.40(x + 20)

0.5x+4=0.4x+8

0.1x+4=8

0.1x=4

x=40

40

Step-by-step explanation:

the revenue of the fitness center, y, is the product of two factors: the number of members and the fee paid by each member. there are 320 members now, but number of members goes down by 10 for each $5 increase in fees, so if x is the number of $5 price increases then members is equal to (320 - 10x). since the fee is currently $45, and the fee increases by $5 for every price bump x, the fee is given by (45 + 5x). so, revenue y is given by y = (320 - 10x)(45 + 5x).

-1/3(x+1)^5

i’m pretty sure this is correct