Lithium has two isotopes.
li-6 and li-7.
li-6 mass = 6.015121amu
li-7 mass = 7.016003amu
lithium mass = 6.94049amu

what is percent abundance of li-6?

i know that there is an equation:
6.9409 = (% abundance li-6 * weight of li-6) + (% abundance li-7 * weight of li-7)

i don't know how to use it.

In november 1987, a massive iceberg broke loose from the antartic ice mass and floated free in the ocean. the chunk of ice was estimated to be 98 mi long, 25 mi wide, and 750 ft thick. a typical backyard swimming pool contains about 24,000 gallons of water. how many of these pools could you fill from the water in this iceberg? (assume the iceberg is a rectangular solid of the above dimensions and consists of water only). express answer in scientific notation.