For what value of a does (1/9)a+1=81a+1 272-a?

Serena is making an experiment. for that, she needs 20 grams of a 52% solution of salt. she has two large bottles of salt water: one with 40% and the other with 70% of salt in them. how much of each must she use to make the solution she needs? i am in need of

The four students in the table below each recorded the time and distance traveled while exercising. exercising distance (miles) time (minutes) gia 2 30 harris 5 50 ian 3 40 jackson 4 80 which list ranks the students from fastest walker to slowest walker? jackson, gia, ian, harris harris, jackson, ian, gia harris, ian, gia, jackson jackson, harris, ian, gia

Aspacecraft can attain a stable orbit 300 kilometers above earth if it reaches a velocity of 7.7 kilometers per second. the formula for a rocket's maximum velocity v in kilometers per second is vequalsminus0.0098tplusc ln upper r, where t is the firing time in seconds, c is the velocity of the exhaust in kilometers per second, and r is the ratio of the mass of the rocket filled with fuel to the mass of the rocket without fuel. find the velocity of a spacecraft whose booster rocket has a mass ratio of 20, an exhaust velocity of 2.1 km/s, and a firing time of 15 s. can the spacecraft achieve a stable orbit 300 km above earth?